Let's address face weight

To discuss face weight, we should first define it.  If you took a three foot square piece of carpet, shaved off all the fibers on top of the carpet, then weighed those fibers, you'd have the carpet's face weight.  This gives you a simple statistic about a carpet usually expressed as "ounces per yard"  or  60oz/yard for example.  

Unfortunately, because it is so simple and seemlingly objective, many retailers have started using face weight as the primary way to compare carpets.   While simple, this can be very deceptive in terms of product quality, mostly because it deals with a quanity figure and has nothing to do with quanity. 

We wouldn't apply this same reasoning to other buying decisions. Would you say that a Quarter Pound burger would be the same if it came from McDonalds, Red Robin, or Morton's Steak House?  They all weigh a quarter of a pound, but clearly there are some differences in terms of quality, value, and price. 

Face weight is only one of several factors that play a key role in determining carpet quality. To truly understand the quality of the carpet, all factors need to be taken into consideration, including, but not limited to: fiber twist, fiber type, guage, and carpet style.