A "party girl" is either angling for free party "favours" so the cost of your punt goes up, or she may provide with the intent to again make you spend more (uncontrollably) as your favourite dealer with benefits, or she needs to get "partied up" in order to engage in sex, whether that brings a good or bad performance. Of course with intoxication there is the risk of no inhibition which may be preyed upon by the BB junkies and of course it could lead to a really messy argument if she loses it during the meet.
All told a "party girl" is a risky and costly venture at the chancey end of the punt scale.
A "420 friendly" girl is less of a problem although she may be too stoned to do much at all or object... in which case what have other punters done with her?...
All in moderation is fine but then again you might be moderate with your meet but she's had x meets before you and whatever in between.
"Party" is a lure like any other, that's why genuine reviews matter more. "Hot Brazillian babe, new in town wants to party hard, super sexy, come baby I do everything!" The only thing true about that ad line? "Come baby" will be mentioned during the encounter, way before the end of your time.