Dumb grout vs. caulk question at plane change in tub
Tackling a long overdue caulk replacement project in our bathroom, and it's been a long time since I've done any tiling so I want to be sure I have my head on straight!
We didn't do the original tile job in our bathroom, and when we first moved in it had grout at the tub/tile plane change. We caulked this over the grout, and now some years on, that is all mildewy so I pulled it out. The grout below was pretty yucky too so I went ahead and took all of that out as well along the seam of the tub and tile.
Question: Do I need to replace the grout, or can I simply clean this seam and then caulk it? I remember when we did our kitchen tilework, we left the seam between counter and backsplash free of grout and caulked it instead, but I'm not sure if this should be the same in a bathroom or if there is some reason you would want grout under the caulk (or grout without any caulk?)
If these factors matter, we have an old house that is settling (which makes me concerned about having any grout at a plane change) and the tub is not level so water pools in one corner (won't even get into that one, but short story is that it is not going to be fixed anytime soon so we just try to be diligent about keeping standing water out of the corner where it's an issue).
Can I just give this a thorough cleaning and caulk, or is there a case to be made for redoing the grout first in this situation? Thank you!