Pope Gregory I declared baths should be only used to cure the sick. Of couse, we read his words different today (like he allowed it) but bathing was considered sinful. There was a belief that bathing invited demonic possession and that the dirt, sweqt, etc. actually repelled demonic forces.

In my part of the world, there are still stories how church was telling people that you should take a bath only on Đurđevdan (and joke is that only Gypsies followed that).

You do know that the devil is lurking from the water don’t you? I guess folk tales cannot be used as proof since they are no written records.