The god entered some women so completely that they became immortal, or very close to it. Bacchus was the god of the grape, of course, so bars are very interesting to maenads. In fact, so interesting that they don't like other creatures of darkness becoming involved. Maenads consider that the violence sparked by the consumption of alcohol belongs to them; that's what they feed off, now that no one formally worships their god. And they are attracted to pride.
Charlaine Harris (2011). “True Blood Omnibus: Dead Until Dark, Living Dead in Dallas, Club Dead”, p.248, Hachette UK