Over the years, I've collected a lot of minis. Many of them were painted when I got them, and a lot of the final paintjobs are... well, sub par. I started painting when I was about ten, and I didn't have anyone to teach me technique, so you can imagine that many of them are true atrocities.
Of course, I'm saving a lot of old paintjobs as a sort of artifact from the era. That said, I've also become quite adept at stripping the paint off of older minis. The method I use most is a 50% Pinesol water solution. You can leave metal miniatures in there for a few hours, and when you pull them out, you can wipe the paint off of them with an old tuthbrush.
The trouble with most stripping methods is if you have any greenstuff on the mini, it will probably dissolve away in the mixture. I don't mind redoing some assembly and gap filling, but I'd rather not have to re-sculpt large portions of a mini due to a botched paintjob.
Janci found an interesting solution to this: Rubbing Alcohol. It seems that the alcohol can eat through acrylic paint at an alarming rate. It is so fast that you can even use it on the end of a cue tip.
Janci stripped this minis' face without touching any of the sculpted area on the mini:
I think that it is interesting that the alcohol has no effect on the primer. I suspect that it will not work on sealed minis, so it is probably best used if you feel like you've just messed up one part of a mini with too thick paint, and don't want to re-do the whole thing.
A nice discovery, to say the least.