Not at all offensive, clear expectations should make the experience more enjoyable for everyone. My only issue would be leaving my glasses in the bathroom, I'd end up walking into a wall...
I like seeing more average guys in porn, but I also tend to like watching more average looking girls too. Not into the fake "beauty" of a lot of the porn industry. The main thing for me is that they seem to actually be enjoying it.
How do you feel about guys coming from work and needing a shower? Obviously should be arranged ahead, but is it a turn off? I work construction and can't go home to shower before hand for certain reasons....