Are they really this stupid? Just adjust the quanitity of each item that you put out and be done with it. I'm sure smarter CPA's than I have correlated the occupancy from the night before and number of buffets sold in the morning. And they have years of historical data to refer to.
Smart messing with the fruit and its good bye Marriott.
For kicks, why not actually keep up with replenish the items (especially the fruit) as they are consumed. You'd be surprised how often the plate of this or that stays empty for 15+ minutes and I finally have to ask them to replenish the pineapple...