"A Great Dentist" joke

A guy and a girl meet at a bar. They get along so well that they
decide to go to the girl's place.
A few drinks later, the guy takes off his shirt and then washes his
hands. He then takes off his pants and washes his hands.
The girl watches him and says, "You must be a dentist!"
The guy, surprised, asks, "Yes... how did you figure that out?"
The girl says, "Easy; you keep washing your hands."
One thing leads to another and they make love. After they are done,
the girl says, "You must be a great dentist."
The guy, now with a boosted ego, says, "Yes, I sure am a great
dentist. How did you figure that one out?"
The girl says, "Easy; I didn't feel a thing!"