For a while I've been making the joke that you could draw a flower when asked for your signature and nobody will care. I've had to pay with other people's cards and signed in print. Nobody cared each time.
until you go to Europe.. make them search for a pen for your 'American' card and you do a simple signature and they look at you (and even tell you) their incredulity to your signature! (happened to me more than once a few months ago, one cashier actually got upset at my simple signature)