Idk, if someone gave me that answer I'd re-ask the question. Or I would assume they are a little slow in the head haha. Obviously the dog "can" bite. I'm asking if he/she "does". I also think that is a silly question, I prefer "can I pet your dog?"
Honestly, I mostly prefer if they just pet him without asking. If they ask it shows apprehension (for the most part) and dogs can sense anxiety and it confuses them and makes them anxious. Especially on-leash. In my experience anyway. If you just come up and pet my lab, he will be your best friend. If you do the whole, shying away while trying to get him to smell your hand first, he will be like "wtf is this human doing, I'm not so sure about this one"
Like I said, that's just me.