So my husband and I decided to change the bathroom floor (and many other things actually). When we took up the tile we discovered the previous home owners just tiled over the existing tile. Is this good or bad? Should we removed the tile and put down a subfloor rated for the bathroom?
Tiling over tile is not unheard of. I wouldn't add any more layers to it though. I'd pull it all out.
As far as pulling out or replacing the subfloor, It depends on a lot of things including how that bottom layer of tiles comes out, how it's constructed, the condition, and what kind of flooring you're considering. It's often a don't-know-until-you-get-there type decision.