It's hard to maintain the reputation of a "good girl". No one will care about the good stuff you do because goodness is expected from you. Instead, people will scrutinize your every move. Even the tiniest mistake you make will be used to villify you and strip you off your "purity". As a "good girl", you are creating a standard of perfect moral behavior that is impossible for any human being to uphold.

In direct contrast, as a "bad girl", people will not expect much from you in terms of morality. You will be free to do whatever the fuck you want. Since you'll already have a bad reputation, when you do good things people will lavish you with praise. No one will care about your morals because no one expects you to have any.

Many will argue that the dating pool is worse for "bad girls" due to the virgin/whore dichotomy which leads men to fuck 'n run, I will argue that this argument only stands for abusive men who mistreat women in general, including "good girls", who they disrespect and cheat on. If these men are eliminated from the dating pool, you will find the men "good girls" and "bad girls" compete over do not give a flying fuck about their reputation. In fact, they might even admire the "bad girl"'s honesty.

Tl;Dr being a "bad girl" is smarter because it doesn't force you to live up to an impossible standard and provides you with complete freedom without significantly hurting your dating pool.