Susiequ
TF
I do not like tiling over paint even if it is well sanded. I prefer to remove it. I have found that using a steamer softens the paint so it can be scraped off quite easily. BUT you must NOT hold the steamer over the paint for more than a few seconds, keep it moving and just do a small area at a time. If you over steam you risk cracking the plaster! I have just had to do two bathrooms this way, fortunately, they were not being fully tiled.