Consider higher density over the amount or weight of the face yarn. This would mean more face yarn with less pile height. The weight of the carpet might be given as ounces per yard, but dealers will seldom tell you the weight. If the pile height is too tall for the amount of yarn, the appearance and wearability deteriorates quickly. Also, a good heat set with lots of twist is important.
	Avoid blends -- Blends might offer the best of both worlds in garments but not on floor coverings.
	Avoid installing carpet in bathrooms and kitchens. Give consideration to not installing carpet on stairs, too. Most warranties do not apply to these areas.
	Consider getting a better installation over a higher quality carpet. An excellent carpet with poor installation  will lose appearance and performance quickly. Good installers will typically start their charges at $4.50/yard  on stretch-in installations. From a professional view point, installers that carry Certification from the American Floor Covering Institute known as CFI are an excellent choice.
	Read the "WEAR WARRANTY" carefully. Most ware warranties are for the reduction of faceyarn. They have nothing to do with the way the carpet will look or for appearance retention. Thus, crushing matting are likely not covered. In most cases, shedding and fuzzing will not be covered either.
	Carpet is generally sold by the square yard, but pricing by the square foot is becoming more popular. (To convert square yardage to square footage multiple by nine, example 1 yard = 9 square feet.) On none pattern carpet, expect the dealer to sell over the yardage of the area to be carpeted by 11 to 20 percent. Where patterns are involved, 20 to 30 percent should be tolerable. Remember too, that carpet normally comes in 12 foot widths. Therefore a 13 foot by 13 foot room will require a 26 foot section of 12 foot wide carpet to fill it and there will be a lot of waste.
	Do not sign any kind of arbitration agreement for resolving disputes. Sign nothing that restricts you using the court system.

	Nylon comes either in Type 6 or Type 66, six generations, Bulk Continuous Filament or Staple, and Branded or Unbranded. Type 6 or Type 66 -- Type 66 from a professional view point holds its color better and is more resistant to stains. DuPont and Monsanto make type 66 nylon. Bulk Continuous Filament or Staple -- Bulk Continuous Filament is called 'BCF' and is continuous filaments of fiber. You will get less shedding with this one. Staple has more bulk, but is not my choice. Branded or Unbranded -- Branded will have either DuPont, Monsanto, Allied, or BASF names on the yarn. Unbranded will likely cost less and will likely be a Type 6 Nylon. Generations -- Nylon has evolved through six generations of improvements and some third generation nylon is still being made. Third generation nylon has  a carbon core to help with static electricity, fourth generation introduce Teflon and Scotchgard to help with soiling, fifth generation nylon accrued stain resistance to protect against common household foods and beverages, and sixth generation nylon could include either crusher resistance or twist retention. In most cases residential carpet will be a fifth generation nylon yarn. Avoid anything less.
	Polyester -- is the second least expensive yarn. It naturally resists stains, comes in vibrant colors, and is resistant to fading. However, it is the second least resilient yarn next to olefin, and is the most oil absorbent. This oil absorption problem means it might be difficult to clean and rapid soiling might be a problem. Teflon, Scotchgard, or similar treatments should help with the oil absorption and soiling problems.
	Corterra -- is a brand new yarn by Shell. Its monocular structure is similar to Polyester, but it is reportedly more resilient than nylon. If so, then it would be the most resilient of all synthetic yarns. It should be resistant to stains and fading. We do not know about the oil absorption problem which would be directly linked to soiling problems. The unlined text is linked to their web site.
	Olefin -- is the least expensive of the yarns, but would be a worthy consideration if you have problems with urine or allergies or if fading or color loss are likely due to excessive sun light or high o-zone levels. A strong disadvantage of this yarn is that it will crush and will not gain its resiliency after cleaning. Avoid buying cut-pile style with low density.
	Wool -- self extinguishes when ignited with a flame. It has great resiliency, however, it is expensive, it stains easily, and it fuzzes easily. Mohair and Silk are similar to Wool in that they too self extinguish with flame. Silk does not have the fuzzing problem that Wool has, but normally is only found in rugs. Mohair comes from goats and is essentially similar to wool. All three are considered protein fibers and will all degrade if  cleaned with a high pH substance.
	Cellulose - Cotton, Sisal, Coir, Sea Grass, Abaca, and Raffia all come from plants. Jute could also be considered in this group, but is commonly used in the backing of very few carpets. Cotton is rare and sometimes not associated with the others. Sisal is the more popular and used to be popular as door-mat material. The Sisal yarn with Sisal pattern, but most Sisal yarn will come in Sisal pattern. Coir, Sea Grass, Abaca, and Raffia will likely come in a Sisal pattern too, and many synthetic copy this style. All but cotton not tolerate wet cleaning and even Host & Capture methods of cleaning will have to be modified to include no wet preconditioning. Cotton will take longer to dry than Wool and will likely require the same type of cleaning. Sisal will shrink if it gets wet while Coir will expand. Some manufacturers will blend Sisal and Coir. Do not expect flawless pattern repeats or meticulous perfection in the appearance of these yarns.

	Velvet is a cut pile that looks fuzzy on top with no distinction of individual yarns. It has no twist and little to no heat set. However, be WARNED. high density cut Velvet can suffer from a phenomenon known as Pooling, Shading, or Water Marking. This is a permanent change in the pile direction of which there are no recognized cures. Furthermore it is not considered a manufacturing defect or the result of an installation error.
	Cable Yarn is a cut pile that looks like cut Berber. Yarns are fat and untwisted and heat setting may vary. Some Cable Yarns have been known to loss twist after cleaning and/or with modest usage.
	Saxony is a cut pile that looks fuzzy on top with little or no distinction of individual yarns. It has modest twist and it ability to maintain its twist will depend upon how good the heat set was during manufacturing and the quality of your installation. It is our choice for 'run of the mill' residential. However, be WARNED. High Density cut pile Carpet can suffer from a phenomenon known as Pooling, Shading, or Water Marking. This is a permanent change in the pile direction of which there are no recognized cures. Furthermore it is not considered a manufacturing defect or the result of an installation error.
	Frieze has the most twist and has a clear distinction between yarn. It is less likely to show footprints. Loop Pile lacks aesthetic appeal for most consumer appeal, but this is our professional choice for commercial installations. Consider this style if you are buying olefin. However, be WARNED. High density Frieze can suffer from a phenomenon known as Pooling, Shading, or Water Marking. This is a permanent change in the pile direction of which there are no recognized cures. Furthermore it is not considered a manufacturing defect or the result of an installation error.
	Berber is named after the group of African tribesmen involved in the rug trade. This is a loop style with very little twist. The yarns are often fat and in the past there have been problems in manufacturing on getting enough latex into the yarn. Avoid Olefin when buying this style.
	Sisal is a new style and there is a Sisal yarn that is a natural product made from trees. Natural rope is sometimes made of Sisal and is used in the old style walkoff mats.

	In general Make sure that you get a diagram of your home with the layout of all seams. Make sure that all cut edges have seaming adhesive placed between the primary and secondary backings. Expect patterned goods to match at all seams. Never allow carpet to be installed over another carpet.
	Stretch in Over Cushion is the preferred choice in most applications but especially in residential installations. If you are buying a rebond cushion make sure that its height does not exceed 7/16th of an inch and that the density is at least 6.5 pounds per cubit foot. A fiber type cushion should be used on stairs. Make sure that your installer does not place cushion seams over carpet seams. Make sure the distance of the tackless strip does not exceed 3/8th of an inch from the baseboard or is less than the thickness of the carpet. If it is too far away, the carpet will have a shaved look next to the baseboard.
	Direct Glue Down is the most stable form of installation and should be considered if usage is going to be extreme.
	Double Glue Down is where cushion is glued to the subfloor with carpet glued onto the cushion. It continues to grow in popularity in commercial use, but is not free of problems.

Check for Stain resistance:

1. Take five yarns from the edge of the carpet.
2. Prepare a solution of dye by placing five drops of red dye into one half ounce of tap water or if the carpet is red, use blue dye. If dye is not available, then red Koolaid or red drink at room temperature will do.
3. Place the yarns in the dye solution for three minutes.
4. Rinse the yarns off with tap water.
5. Compare the yarns to the color of the carpet. If the yarns took on a stain, then there may be a problem inherent in the manufacturing of the carpet. Contact the dealer at once or call me.
   

   The yarn on the left is stain resist; the one on the right is not.

Check for defect in the latex

Check for heat set, (Twist for cut pile yarn)

Installation check list

Get a written agreement on where all seams are going to be laid. Do not allow seams to run parallel with natural light sources such as sliding-glass-doors. Make sure that no seam is placed perpendicular to doorway or immediately across entrances, except for doorways. Make sure that the carpet is laid perpendicular to the cushion seams. Where this cannot happen, make sure that cushion seams are at least six inches away from carpet seams.

	Make sure that your carpet is power stretched with a power stretcher. No power stretching can lead to buckling and delamination. Power Stretchers are long pole apparatus with teeth.
	Make sure that the cushion seams are taped. If the tape is not in place, then gaps can form in the cushion seam making a dark line in the carpet.
	Make sure that all carpet seams have a seaming adhesive applied to the cut edges. Seam sealers generally have ultra-violet dyes that will shine under a black light. If no seaming adhesive is applied this can lead to fray edges and pulled loops in the seam.