This topic comes up over and over and over... Now ask yourself, if fabric bleeding were not a significant problem, why would the topic keep coming up? I recently bought Harriet Hargrave's book, "From Fiber to Fabric". She doesn't pre-wash everything, but she has an exhaustive set of tests that she uses to determine whether a fabric should be pre-washed. What she does, with a good understanding of the manufacturing process, is technically correct, and it takes into account differences in water, detergent, etc. For me, it's easier to pre-wash all of it than to run through the tests. I don't mind washing, pressing, and re-folding the fabric, and I like knowing that 99% of my fabrics are ready to go with no worries. The other 1% are fabrics that will be used in OBW, pre-cuts, or really large yardage that I will wash in increments when I'm ready to use it.