From Catija's answer there: 'or focus on whether there's any (specific) cultural etiquette in a situation.' --> So, if there really is a specific cultural etiquette here (which there very well may be), focus on that, instead of whether it is rude?
Like suggested here: Don't ask whether it's rude to wear a sari to a wedding as a westerner, ask "As an American attending an Indian wedding in India, what is the etiquette regarding wearing a sari as a non-Indian? [question body explains in more detail]"