I prefer washing my fabrics before using them, and not just the darker fabrics. We live in an apartment now, so I can't just go down to the basement to throw the fabric in the washer and dryer, so many times I wash the fabric in the sink. I am amazed when some of the lighter fabrics bleed and some of the darker fabrics don't, and then I'm very glad I have washed it - especially since many of the items I make are made to be sold or as gifts, and I would hate to have something I made come back with a dissatisfied customer. Not good PR. I cut the corners of the fabric with a small triangular cut, which not only lets me know if a fabric is washed or not, but it cuts down on the fraying when the fabric is washed - a tip I picked up somewhere along the line.