One of the previous owners of our new flat thought it'd be a good idea to paint the tiles in the toilet -- twice!
We've been using a paint scratcher to remove the paint
The problem: This takes too long (~120 tiles) and is tiring (as you need to use quite a bit of force and you take an inconvenient angle).
Thus we tried chemicals: Hydrochloric acid (no effect at all), graffiti remover (worked a bit, but generally made things messier/stickier).
I'm sure there is something we haven't thought of yet and gets the job done in a faster, less work intensive way.
Uh, yeah, and how do I get the paint out of the seam?