A few tricks that can catch meeting that a more or less guaranteed to be useless (in IT):

* Does it have less than 10 people attending?

* It there an here an agenda?

* Is there more technical people than managers?

* Do you know why you've been asked to attend?

If you can answer "No" to any of those questions, you're going to have a bad time. Now you can have meetings where you answer yes to all of the above, and it's still useless, but the chances are lower.