Am I the only one that considers it incredibly RUDE to approach celebs and ask for an autograph or fawn all over them? I wouldn't presume to do that in a million years. If you're in direct proximity and they speak to you, of course, that's a different situation, but randomly walking up to them and saying you're a huge fan (as if they haven't heard that a million times) is just desperate.
As an aside, half the folks I see on the street look like they've been programmed and walk around with their mouth open.