How would I know? A rhetorical question look just like any other question. The only difference is in the intent of the person asking it. Typically he do not want to hear your answer, but instead he want to answer it himself. That also gives us a clue on how to recognize rhetorical questions.
If it touch on some controversial subject or come from a person handing out pamphlets it could well be the lead-in to a 'sermon' about how The Right to Bare Arms is constitutional and essential in a free country or about gayness being a choice or about Trump being an idiot, ...etc.
Nah, but there are other great examples inside the question board. I could give examples, but better not... I'll just be told again that i hate all that sort of questions... Hmm.