I prewash all my fabrics, and I don't buy precuts. Being asthmatic, I prefer to be safe than sorry. Also, I've had the situation where the fabric I bought for a project bled horribly -- typically, a red fabric. I found a product online, Rit Dye Setter (I have no financial interest -- just happen to use the product) which is what I wash my fabrics in, starting with the lightest shade through the most intense vibrant colors. That effectively removes the chemicals that can cause problems. I prefer to adopt Murphy's Law when it comes to fabric dyes bleeding and fabrics shrinking. I also press my fabric before I cut. All I have to do is just consider the risk: All that work, money and time just flushed because failed to wash/set the dye. NO, I won't take that risk. As I understand it, the bleeding problem occurs because the fabric dyes used these days are chemical and not organic, and are much more prone to bleeding. I simply can't afford to take the financial risk of ruining a quilt. I don't sell quilts or make quilts for anyone else -- I make them for gifts, but I'm on a limited income, so I can't afford to risk messing up a gift.