My wife and I were enjoying some chain texmex fajitas last night, and somehow we ended up in a conversation with our waiter wherein he started talking about how much food the restaurant wastes: they're constantly throwing out tortillas, rice, etc. He became very serious and pointed out how terrible it is to waste food when there are so many people starving in the world.
Now, I don't think anyone actually supports the wasting of food, or feels like it's unjust that people in the world go hungry every day, but it seems like an odd topic for a waiter to discuss while his patrons' mouths are stuffed with beefy tortillaed goodness.
His service overall was fine, and it certainly didn't affect his tip, but it just seems like as a waiter you probably shouldn't make your patrons feel guilty about eating.