When I moved into my house the bathroom tiles in the shower were in great shape, and very cool 1950s decorative design. The grout on the other hand was rust stained pretty badly and in some areas needed repaired. This is a pretty common issue when the grout sealant wears away over time.
There were also some issues with the caulk, where it appeared over the years people had added new layers of caulk on top of layers that had mold on it. So kind of a water proofed mold and mildew line of caulk that was very resistant to cleaning.
If you own a home, or rent a home and want to make sure you can get your security deposit back, at some point there will come a time when you need to make repairs and/or alterations to drywall. In my case, the previous owners had a habit of adding telephone and cable TV connections all over the place and not removing the ones they were no longer using.