I'm working on a Scarlett commission that's going to a little boy and so I dyed the figure first and now I'm painting over the dye (black dye, charcoal colored paint) so it should hold up well. I've found on Sigmas that the color saturation for dying depends on whether the part has factory paint or not. Where there's factory paint, it won't be as dark, but it's usually just accents that can be painted over easily. I like the fact that the dye goes into all the joints and with gray or black paint on black dye it should mask rubs really well. I've not tried other colors. Obviously you're not going to get a dark figure to dye tan or something, so you're pretty limited with dye. On this Scarlett, I've sealed what's done with Future floor finish...and the next day I knocked her over, and she hit against the hard edge of a shelf...and the paint is unmarred.
Eventually I'll go back and fix all kiddo's customs with that finish.
On joints that rub a lot, I've boiled and popped the part (Sigmas, of course) and sanded down both the male and female join parts for more clearance.