Describes a woman who performs oral sex frequently, and as a result shows some skill. Implies prostitution, sluttiness. The idea is that she'd have to be efficient to fit all her men/johns in. If she were sloppy, she'd never have time for anything else.
A precise woman makes you come quickly, not hard. Usually derogatory, although if the woman is not ashamed of her sexual prowess, can be complimentary (the latter is rare.)
I know that ho gets around a lot, she's just too precise to be a prude.