damnit... forgot the link to the ajax-spray, here it is:
http://www.colgate.se/app/Colgate/SE/HomePage.cvsp (just don't forget to change the language up in the corner!)
I have tried two different brands, one called Cillit Bang (website), either the kitchen cleaner or bathroom cleaner works.
or Ajax (website here, but you have to change the language on top and click your way to householdcare, to a spray called Ajax Universal Spray).
Pick a jar or something similiar and spray enough so it covers the miniatures, let them soak for 24 hours and then use hot water and a stiff toothbrush to scrape off the paint. If the mini has been painted with multiple layers it might take more than one dip to get all the paint to come off.
Also use a small needle if there are spots with details like eyes that might not get loosened by the sprays.
It takes a bit longer than brakefluid or acetone but it doesn't warp or destroy plastics and is nowhere near as dangerous to your health. Plus you can use it to clean your house!
Hope it helps!