I am about to do my second paying job just wanted to double check a few things since never tiled onto a painted surface before
Tiling onto a painted wall ,will do tape test and then if paint comes off sand and score the wall, would you then seal the wall before tiling or will it be ok just to tile straight onto. I was going to use tub stuff so can I use any sealant or would you guys recommmend one.
If the paint is ok would you still score it anyway and then seal ?

Personally i always try to remove most of the paint before tiling as you can never be sure how well the paint is bonded on the wall....

if you are going to prime use something like this


BAL Prime APD
A modified acrylic polymer dispersion for use as a primer for a variety of backgrounds/bases prior to fixing ceramic tiles, mosaics and natural stone and prior to the application of levelling compound and the BAL WP1 TANKING SYSTEM. BAL PRIME APD isolates products containing calcium sulphate such as gypsum plaster and anhydrite screeds from cement-based adhesives, thus minimising the risk of reaction between the two materials.

Also suitable for use on cement:sand rendering, blockwork, plasterboard, cement:sand screeds and timber. It also provides surface strength to friable surfaces and reduces the porosity of porous backgrounds/bases, thus preventing the formation of air bubbles and prolonging the flow time with levelling compounds and extending the open time of tile adhesives. The primer is blue in colour to help ensure that a complete and even coating is obtained.