http://www.wisegeek.com/what-is-thread-count.htm
The general wisdom is that a thread count of higher than 100 is desirable --these fabrics are known as percale -- with somewhere above 180 being ideal. While fabrics are available with thread counts up to 1000, anything in excess of 400 is considered by most to be simply extraneous.
**this is about sheets/linens
http://en.wikipedia.org/wiki/Units_o...t#Thread_count
Thread count is often used as a measure of fabric quality, so that "standard" cotton thread counts are around 150 while good-quality sheets start at 180 and a count of 200 or higher is considered percale.