I tested some ink pads, because I also wanted to make some fabric patches. I have pictures and stuff of before and after washing.
Before washing: http://flickr.com/photos/kylanicole/2631375159/in/set-72157603991067128/
After Washing: http://flickr.com/photos/kylanicole/2632198116/in/set-72157603991067128/
Black ink on off-white cotton calico fabric. Heat-set, then washed in cold water with mild detergent; air dried.
Staz-On is dark on cloth, but bleeds before and after washing.
VersaCraft produces a nice crisp print, but is very light, and washed out almost completely.
VersaFine left a clean print, and was darker than VersaCraft, but still fairly light. Faded a little after washing.
I have yet to find an ink pad that I really love for cloth. I don't think I have ever tried a dye ink pad, although logically, dye would be better on fabric than solvent or pigment, heh X] I just don't have any dye ink *shrug*