Interesting to see all the followups. I had no idea that anyone cared about this. Reminds me of guys who don't like people touching their cars. I'd encourage all the folks advising the OP to be curt or to ostentatiously rub out the smudge to imagine a guy in a polo shirt wearing Ray-Bans. Perhaps his collar is turned up. Now imagine this man behaving the same way after someone touches the finish on his Corvette. You are the geek equivalent of that guy.