Never happened to me. Agencies i use do not do B&S for a start. Secondly if i go all the trouble to go to Montreal, take the metro, and so on, obviously im super exited at what is coming next

. It did happened a few times the girl wasn't "as hot as i had pictured in my head" base on the website pictures, but they were still attractive and i didn't just book them for look (reviews, reputation etc) so i ended up having a real good service anyway.
I think for me to say "it won't work", it would need to be a combination of both lack of physical attraction combine with cold attitude. So far i been lucky to never really have a "bitchy attitude" as in very unpleasant, this would probably be the "ok i think we will stop it there" scenario, but i had a couple times where the SPs felt "cold" (could be she was shy, new, inexperienced) and most of these were to blame partially on me for having book someone new, unreviewed, and/or they were "last minute plan" as in it was either i go back home with my $ but no fun, or i see someone that is less "safe" or "sure value" if you prefer.