Refused once on location? No. But a few rare times (on more than 100) i could see the SP was "powering trough" in automatic pilot, probably because she didn't like my physical look (especially at my fattest). One i can remember was kinda new and i guess i shouldn't had book her (pictures were so good tough). Otherwise sometimes it may had just been lack of chemistry or SPs just not into their job at all (sometimes you can see later by reviews if others had better experiences or not).
I do know tough that due to my very vocal opinions at some points (i did tried hard to tone down on this here and mostly avoid replying to SP on social media if im disagreeing with them) some providers would likely not book with me if they knew it was me. Granted the majority of those ones, i have no desire to book them either so its not really an issue.
Otherwise i try to follow the guidelines as strickly as i can (no time waste in text, hygiene of course, and being as friendly as i can). And i do my "chores" when booking and try to go with the SPs who not only attrack me physically but have good reviews or seem friendly online (if indy), overall my succes rate is very high.