A circular plate, I know I'm about to eat a home cooked meal. Treys are just plain disgusting to begin with. Everytime I see a tray, someone's got fast food. Hell, many rappers have had the name Trey too after the thing. Stupid stupid stupid. This world is coming to crap.
Trays can be cleaned and sanitised just the same as any other dish.
They are also very helpful for people with autism and/or other issues who can not bear to eat different kinds or colours of foods that are touching each other.
I imagine they could be useful in a buffet to stop different flavours of food contaminating each other without the need to carry many dishes, and to me less dirty dishes is less disgusting.