A Wisconsin man called police after one of his favorite restaurants refused to keep feeding him, even though it was "All You Can Eat." You can see the story here from WTMJ-TV:
I'm TOTALLY on his side. I'm not proud of it, but growing up my mentality with "All-You-Can-Eat" was that I wanted to be the customer that the company lost money on. We didn't have much money growing up, so I always wanted to at least get my money's worth.
The All-You-Can-Eat business model works because you make LOTS of money on a few people and SOME money on most people. It also includes the fact that you're going to lose money on a few customers.
I don't go in and try and "get my money's worth" anymore - I try and stop eating when I'm full. But in general if you're going to advertise it's "All You Can Eat," then it should be. Even if you have to add and asterisk that says "*within one hour" or something like that.