Once in Buenos Aires I took an incall service. When I arrived to the guy's place I saw the pictures were real, he was a totally nice guy, but the chemistry was just not there. When he was sucking my flaccid dick, I interrupted the action, apologized, paid him his fee, and left.
Besides pros, something like that used to happen to me quite often with regular hookups. I am doing much better since I am videoconferencing before meeting.