I agree with Eryka. I've never had a condensation problem aboard that was traceable to showering on the boat. I read it over and over but have never run into it or talked to anyone else with the issue. Everyone has heard it or read it though ... another cut and paste urban legend perhaps?
The only problems i've experienced is in the one i've got, it wasn't really made of water-proof stuff and the plywood has delaminated and warped past the screws holding id down, and soap seems to be the nemesis of teak oil. I may have made it sound like a big deal earlier but i haven't had much experience with it, i just got my hot water working, i just don't like to leave water lying around as I can't take spontaneous drying for granted.