I've noticed since I've gotten married, when I have to give my last name the person requesting it often tilts their head, furrows their brow and says "Isaac? But you're a redhead, surely you're Irish, so you must be married!"
I've never looked at someone and even questioned their last name and how it did/didn't match their appearance.
Though, we had a regular customer at Lowe's and her last name was Shoemaker. That did tickle me a little bit.