My understanding was that the early Baptists in England practiced baptism by affusion (basically slinging a bucket of water over someone). I’m not sure why they did that rather than immersion. Maybe to avoid official disproval, maybe a cultural aversion to completely covering the body in water (I believe that was regarded as being very bad for the health at the time).
I think you are correct. In those days there was a widespread belief that bathing was unhealthy.