See my comments under “How do I get ready for tile? “
Yes, both situations are feasible, and in certain situations very practical. As noted in my previous comments, the surface of the existing tile, wood, or vinyl must be stable and firm, without compromises in the surface that will accept either the new tile, or the paint. It is imperative that anything that is covered is stable and without compromise. The application of a painted surface, over an existing tile surface certainly can be accomplished. However, caution must be taken to ensure that the paint bonds to the surface of the tile. In many cases the existing tile will be a ceramic tile that has a glazed surface. If this is the case, additional care must be taken to ensure that the receiving surface is prepared to accept the new application of paint. There are special primers that have been manufactured to promote the adhesion of a spray, roller or brush application of a coating, on the top of a glazed tile. These primers must be carefully applied and adequate ventilation ensured, to reduce the amount of fumes generated by the application. In some instances, light sand blasting or mechanical sanding of the tile surface, maybe required to produce a surface that will promote bonding of the new application. Remember, the key to a successful project that applies a new sprayed, rolled or brushed surface, on an existing surface, is the bonding of the new application to the old surface.