1. Hygiene is part of it. Shaved my pubic hair and right away two of my regulars started doing BLS when they weren't before.
2. The girl declines your tip. Had this happen with three MPAs. They say because I'm "super cute".
3. You notice mileage getting higher during the session or on repeat visits. I've had MPAs that did only LFK at the beginning of a session, but were devouring my mouth near the end. Also had girls that did CIM or rimming on me with no upcharge after the 2nd or 3rd session.