I am a vegetarian and they usually have labels for the dishes at buffets. But, they don't always have ingredients listed so I always talk with the chefs behind the food. I just get one of them to kind of go through what is safe and not (especially what has chicken/beef broth since you can't see that)
We've asked our server before for help and usually he'll tell a chef & he might come out to your table to show you what you can eat. A few times though the chef never came so that's when I started just directly asking the chef.
I've eaten at Chef Mickey's, Crystal Palace, Hollywood & Vine, & Bomas. The only one I don't like is Bomas and not for lack of vegie options, but because of the food tastes. All of them though the chefs were helpful.