Ah...as many answers as there are quilters.
Everything that comes home is washed - warm water with color catcher and dried in the dryer. Then it's ironed and put on a comic board with information as to manufacturer, collection, width and yardage. The only exception to washing has been pre-cuts which I tend to avoid for just that reason.
You'd think reds are the key bleeding colors, but I've had lots of color catchers colored from greens and purples.