Bob from Superior Threads discusses this topic in his classes. If you ever get the chance to take a class, I highly recommend it. They are free, he does NOT do a "hard sell" to get to to buy his product, and they are very entertaining and informative. There is quite a bit of information on the "education" tab of Superior's website. This page is where he discusses the "cotton vs poly" debate.
http://www.superiorthreads.com/educa...zing-substance