Grout is the part that was designed to fail first
Grout is sacrificial by design — it gives up so the tile and the wall behind it do not — and beach-county bathrooms accelerate the schedule. Permanent humidity keeps joints damp, rental showers run like hotel showers, and the sand that rides in on every beach day works into floor joints like a mild abrasive. The visible symptoms — powdery joints, dark lines that will not scrub clean, a corner bead peeling loose — are maintenance items. The invisible one is the reason to act: failed grout and caulk in a shower is a slow water leak into the wall cavity, and in this climate that cavity does not dry on its own.
A proper repair regrouts rather than smears: failed joints raked out to depth, matched grout packed and tooled, the tile-to-tub and corner joints finished in silicone because rigid grout in a moving joint is why the corner failed in the first place. Individual cracked or drummy tiles lift and reset with matched stock — hosts learn to keep a box of attic spares for exactly this — and loose soap dishes and towel bars re-anchor into something solid instead of back into the same crumbled hole.