Sixties and seventies tracts, and salt in everything.

Housing from the sixties onwards mostly uses fiberglass or acrylic tub-and-shower units rather than steel tubs in tiled alcoves. Those don't chip and they don't rust. They go dull and chalky, they scratch, and they develop fine cracks around the drain where the floor flexes underfoot. Preparation is mostly sanding rather than filling, and the result is the same hard, smooth, non-porous surface.

Closer to the water there are older beach cottages and duplexes with steel tubs and original tile, and those behave like anything else pre-war.

Salt air is the local factor. It's hard on grout and hard on ventilation, and bathrooms near the sand often have mold in the grout lines. Surface mold cleans off before we coat. Mold that's being fed by a leak comes back through, and we'll tell you if that's what we find.