We see Molly being shy and awkward, but mostly I think it's that damnable crush on Sherlock that makes her that way.

I think she would be very good with her hands -- good, in general, at giving another person pleasure -- but it would take a bit of doing to get her to be selfish. So I think she sometimes has difficulty reaching orgasm.

(Tempted, based on what was written above, to pair her with Joe Dawson. Probably do them both good.)