Good girls don't. But she does, and she's not afraid to admit it.
Always Female due to the Double Standard, the Good Bad Girl is less chaste than her fellow female characters. Ever since her figure developed, boys have been making passes at her — and she's been accepting some. In fact, shockingly, she probably even takes the initiative in going after men sometimes. Consequently, she's built up a notorious sexual history around them (which may, however, be exaggerated — many a Good Bad Girl eventually settles for monogamy after they have experienced all that men can offer).
She may get around, and she may not mind showing off her figure, but she is unambiguously good.
She (and her most trusting friends) can't understand why people believe that it's bad for a woman to like sex as much as she does, nor does she internalize the notion that All Women Are Prudes. She's not The Vamp, and she's not even a Gold Digger. Sex for her is not just part of her zeal for living but also of a certain benevolent nature which extends to her non-sexual friendships. She tends to feel sorry when a man isn't getting any — though not necessarily a willing partner for any man: she's unlikely to stray if married to a husband who's good in bed, but if she's unattached, she could fall for her Spear Counterpart, the Chivalrous Pervert, in a heartbeat.
Like her Spear Counterpart, the Chivalrous Pervert, the Good Bad Girl is very likely to also be a female Ethical Slut with a benevolent For Happiness morality. However, it could also be that some part of her still believes that Sex Is Evil, making her feel guilty about her "immoral" horniness and overcompensate for it a bit.
If the Good Bad Girl actually decides to do for pay what most Good Bad Girls do only for fun, she will become a Hooker with a Heart of Gold. If boys actually want to be with her due to her experience, then it's My Girl Is a Slut. See also Shameless Fanservice Girl.
