From David Letterman,
Top Ten Signs You're at a Bad Trek Convention

10. Its being held in a parking lot of a 7-11.
9. When you count the number of Spock Ears, you get an odd number.
8. All the hookers look like Klingons.
7. They start serving snacks called "Spockwiches".
6. People with Moe haircuts keep wandering in from the 3 Stooges convention down the hall.
5. The Enterprise looks like an RV wrapped in paper-mach�.
4. The keynote speaker is Shatner's hairpiece.
3. People flip the bird when you attempt the Vulcan hand sign.
2. Some guy wanders around in a trench coat, asking people if they want to see his 'phaser'.

And the Number One sign you're at a bad Trek Convention...
1. Someone yells, "Beam me up, Skippy!"