No, I don’t think that’s weird at all.
I know many who fantasise about enforced cleanliness. Like being dragged to the bath by a strict nanny, governess or babysitter. Perhaps they’ve been caught playing with themselves, and their sordid filthiness must be cleansed, prior to a good hard spanking.
Often fantasies are reactions against formative experiences. Like being brought up in a spotless environment, and being expected to keep oneself clean at all times. The erotic mind repurposes this restrictions, imagining the arousingly humiliating consequences of breaking such rules.
The warm, soothing waters of a private bathroom are where many first learn to masturbate. It shouldn’t be a surprise then that the bath is a site of immense erotic significance for many, and that some might find it very exciting indeed to fantasise about dirtying themselves, and being forcefully made clean…