Tsunami has it right.
If you look at the description of the each subform, they generally do a pretty good job of explaining what that subform is about. For example if I look at the "pokemon" section, I could see that
Stark mountain would probably be the best place to lurk if you want to find about pokemon related stuff due to the fact it's description is: "Diamond/Pearl/Platinum/Heart Gold/Soul Silver discussion."
Similarly I could see that I should not post in Firebot Development Lab
[IMG]
you could always play it safe and lurk everywhere.