Agree with the comments about tidying up down below, since i've started doing that it has made a difference to the amount of enthusiasm they have for doing OWO, never had what I thought was a problem, but nowadays they really go to town on the old chap.
With regards to the telling them in advance you are a bit overweight, i did do that once, when i was about 15 and a half stone, i turned up and she laughed as she thought i was fine and would be well over 20 stone, having said that she still accepted the booking, hope it works out well for the guy, and with the right woman it will.