@Derriel Cribbs - see my post from a 1-2 years ago.. https://www.biggerpockets.com/forums/522/topics/37...
In this rehab post I specifically run into your same situation. What I did was demo and remove the floor tile and old mortar (up to 2" thick total). I then leveled the whole floor with plywood. Then installed new tile (with cement board, etc.. the right way). Then I hired a professional tile sprayer (look on Angie's List) and for $850 he sprayed all the wall tile bright white. It wasn't a perfect job, but it did come out really nice for a rental. And I've checked on it and thankfully have not had any issues in the past 18 months.
What's important after the painting is done on the tile is the maintenance. NO bleach products. And your tile refinisher will give you a specific list of "safe to use" cleaners for the area.
In the end, I think the bathroom was under $2K completely redone and total time it took was only a few days (vs a week plus with full demo and rebuild of a new bathroom).
If you're doing a rental... I say do a new tile floor and paint the rest.