We are talking about cultural bias, accuracy is not required, after all intelligence is not really really "acting white".
=========================================
If you are pretending to be something you are not, you MUST be accurate. or you appear to be a dork.
If I dress in a Mexican charro suit and run around Guadalajara, I would be considered a true idiot if I spoke with a gringo accent, or misused Mexican slang expressions.
Dressed as an American, it would be no big deal.