I'm a programmer/developer. There are ad-hoc data requests that get routed to me, and a number of systems I've built over the years that I still support, but if there are no requests and no one needs anything changed/updated/investigated, I don't have anything immediate to do. I have weekly meetings with my manager, and it's her job to make sure I'm earning my pay, not mine. As far as both of us are concerned, if I'm doing everything I'm supposed to be doing, I'm fine.
Blatant non-humble brag: I've been told that I work faster than pretty much any other programmer anyone has ever seen. Two years ago, they cut my group from four programmers down to two, and six months later cut the other guy, leaving just me. I've been supporting all the systems, and doing all the ad-hocs, ever since. And I still spend half my time on Facebook or DTF.
Basically, the shit's getting done, everyone's happy. If I can do the work of four people and still goof off half the time, more power to me. If the shit wasn't getting done, they might check into it. I make sure that that doesn't happen.