Rudy Giuliani is having too much fun. He is laughing at his own supposed cleverness.
Laughing openly at Barack Obama’s having been a community organizer was unseemly. I agree with Giuliani that it’s a relatively lightweight job for a future President, but it should have been handled with a much more subtle touch — not open mockery. Actually, the words of Giuliani’s speech on this point were subtle enough, but Giuliani read them much too broadly. (Further, community organizer is not Obama’s last position (the Senate is), but it does seem to have been his most formative job.)
Much of the rest of the words of Giuliani’s speech are OK — and there are some good lines — but the tone of his speech is a bit off, especially in the first 5-10 minutes.