An old co-worker of mine used to work for a company that made flight simulators. He said his manager would stand in the front foyer on the 2nd floor and make notes of who arrived after 9:00am.
I would have fun trolling such a boss. When I was younger, I would stress about job security; work OT whenever asked, say yes to every request, etc.
Now that I'm in my late 30s... I'm finding I have more self-confidence than I've ever had in my life. Couple that with a general sense of professional ennui that's been steadily building over the last few years, and you get someone who just doesn't care if you fire him and acts accordingly.