My bathroom has 2 layers of tile and the woman who owned it before me tried to remove the tile. ( she did about a 1 ft square before she gave up- that's how I know there is 2 layers) she was very proud of the carpet she GLUED to the floor with contractors glue!! YUCK!! I am going to rip the carpet out and put in new tile. Can I just pour floor leveler in where she chipped it out with a SKREWDRIVER and then tile over or do I need to chisel it all out and start over? My house was built in 1908 but is solid. The tub is cast iron with enamel. My boyfriend thinks we may even need to take the tub out. Is that right? There was a claw foot tub still here from the bathroom so I assume that at least there is one layer of tile under the tub.

Being an almost 100 year-old house, I'd think the best thing is to rip it all out, start anew.

XenoSapien

I would just bite the bullet and rip it all up. It might take a bit more time and effort but it will be a lot more permanent and will look a load better.

Rip it all out, start over. Spending all that time to put it OVER somebody else's mess isn't going to achieve fixing the mess. If any of that is done wrong, you'll pay in the end... have to do it AGAIN.

I Agree With All The Above, Tear It Out, And Start Over, They May Of Tiled Over Problems That Will Bite You Later. Say Like A Leaky Toilet.
Especially If You Plan To Stay Here For A While Just Do It Right One Time.