Tiling over a painted wall

[Deansplit]

Does the paint need to be removed from a painted plastered wall before tiling? I realise the tiles are relying on the adhesion of the paint to the plaster, so is it advisable? I've not heard of people having to sand painted walls back to bare p;laster in order to just tile though... The paint is firm, not flaking anywhere.

Or can I use a good bonding agent on top of the paint (not PVA, I know that)

Thx

 

[footprints]

I have done it lots of times as long as the paint is sound, I score the wall all over with one of these.

http://www.amazon.co.uk/Plasplugs-Tlc207-Series-Tile-Scribe/dp/B00534856Y

And then tile away.