If you use a color catcher, how do you tell if it has worked enough so you won't have any more unacceptable bleeding--even if it seems to have gathered up all the bleeding from fabric, don't you have to go through a second wash with a new color catcher to see if the excess dye is really gone? I'm thinking especially of batiks.
Here's a resource about color catchers:
They tested both the Shout and the Carbona color catchers and their opinion was that they didn't work as claimed. I'm confused.