Do Christians even scratch themselves without stopping to wonder if it is sinful?

It's amazing, but highly amusing for us atheists up to a point, to see the number of crazy questions about whether this or that is a sin here on Yahoo Answers. I kinda feel like the Simpsons family when they are laughing at Homer spinning around and around trying to see something Bart wrote on the back of his head in pen, but then they all stop laughing and start to look worried and sorry for Homer.