In order to access classified information, you must posses two things: 1) the appropriate clearance level (confidential, secret, top secret) 2) a need to know

So even possessing the appropriate clearance level doesn't give you the right to just start reading anything that interests you on a classified network. You're supposed to have a "need to know" in case you're questioned about it.

We always get stuff here (contractor on AFB) about "don't read this or that" or else you could be in trouble. But I've never heard of anyone actually getting in trouble.

I never saw anything in writing, but after the Bradley Manning leaks we got a SHIT TON of briefs about not visiting WL, no looking at the leaked docs, and a whole lot of other "don'ts". Never heard of anyone visiting the site after that, and never heard of any shit rolling down from people violating the orders.