It does bring up an interesting point though, I mean how often have you walked up to see an interesting bike and the 1st thing you want to do is sit on it and try it on for size? I mean for me it's a real desire, to see what it feels like, does it feel as good as it looks. But most of us realize that's a no no. In some cases I have waited around, looking very interested in the bike, hoping the owner will show up and then "asking" if I could sit on it.
Funny as a biker we feel that our bike has been raped if someone else sits on it, but its acceptable if we give permission. Kinda like we are proud that someone else has taken an interest.