First of all: "Yes, believe it or not, April 1793 was the beginning of time for the 100% cotton terry towel. Hey, I am not making this up. "
I've heard a lot of misconceptions on this forum and others but that has to be one of the top 10. Terry weaves where first developed in Turkey, probably sometime in the middle ages. The Cotton Gin was merely a machine to separate the cotton fibers in the Boll from the seed thus allowing the mass preparation of cotton before spinning into yarn. Before that it had to be hand picked and was very time consuming. In fact, the Cotton Gin was probably the single machine that boosted the demand for slaves in the South because it allowed for increased cotton production.
Now to the rest:
Terry cloth does not mean all cotton. Terry is a woven or knitted fabric of any fiber, either natural such as cotton or even silk, or of man made plastics such as polyester. Weaving and knitting are methods of assembling spun thread into a fabric.
Microfiber does not mean polyester. Microfibers are available in many forms from polyester (the first material used to make microfber) to rayon, to nylon, to acetate to plant materails such as cellulose (cotton and others.) In a nutshell Microfiber refers to any yarn of any origin (natural or man made) that is below a certain diameter. If anyone wants the technical defintition with all the numbers I'll be glad to post it.
Just because the label says 100% Cotton does not mean it really is. Beware of imports from such places as China. Korea, India, Pakistan, and others. Also beware of misleading labels that say things such as 100% Cotton Loops, this only means the loop is cotton but the rest is God knows what.
Just because the label says Made in USA does not mean it is, beware of importers who change labels!
Just because the towel is made in the USA does not mean it is a superior quality. Sweat shops produce some mighty frightening stuff!
Just because the towel is imported does not mean it is of inferior quality.
Just because something is all cotton doesn't mean it won't scratch. An extreme example would be cotton burlap, it surely would scratch!!
Just because something is made of microfiber yarns doesn't mean it won't scratch.
Therefore based on the above info you can understand that:
Terrycloth can be made with microfiber yarns. In fact, I've never seen a towel used in the way we do that is not Terry or Velour (cut loops Terry.)
The ONLY way for a non technical consumer to know for sure that an item is really cotton is to perform a simple burn test. This thread should help:
http://autopia.org/forums/showthread.php?s=&threadid=20801&highlight=burn+chart
The CD test is not 100% accurate. The CD surface is MUCH softer than your car's. Be careful not to rub hard on the CD, just wipe like you would on your car. If the CD does not scratch then it is probabl that the towel won't scratch the car. If the towel does scratch the CD then it does not necessarily mean it will scratch your car, it only means use some caution and check it in an out of the way spot first.
Stay away from cheap imports or bulk store purchases. While some may be safe chances are they are not, they are typically mislabeled and almost always made from scrap yarn and not pure virgin yarn. Why be cheap with your towels and ruin your $30,000 car? It makes no sense to be cheap on towels and related fabric items, they are the single product that can ruin your car faster than you can imagine. Spending a few bucks more on a quality item is well worth the peace of mind.
All the quality items sold by the companies that support these forums are fine products, it is just a matter of personal taste as to what you like best.