As long as you left some for the other patrons, and took your plate back to your table, I don’t see much of a problem. But I’ve seen people just sit down in front of the buffet, right where the shrimp or lobster tails or whatever are, and just start eating right there.

The other thing I’ve heard of was someone coming into the buffet at lunchtime, having lunch, and then just staying until dinner (without paying again)

One (really really good) Chinese buffet I’ve gone to twice gives you a coupon for a single lobster. The rest is all you can eat, but they had to limit the lobster (probably because of the people who exaggerated)