Not that we'd ever spent very much time thinking about it, but we were sort of under the impression that when making cheeseburgers, the cheese-type toppings are placed on the burger to melt while still on the grill, right before it is done.

That is how we do it. Obviously, we have a lot to learn.
Eugene writes:

My friend Dmitriy went to the McDonald's on First Avenue 71st st in Manhattan to pick up lunch for us. I decided to go with the new Mushroom and Swiss Angus Burger. I'm not a big fan of McDonalds but decided to give it another go.

Unfortunately, it was a bad decision. Dmitriy brings the food back to our college, on 68th and Lexington, and I take a bite, tasting delicious mushroom and swiss cheese, but that is the only thing I taste. I open up the sandwich to see that all I have is just that-mushroom and swiss cheese, no burger, no meat. It was too late to go back to that McDonald's to exchange it because I had class starting in 15 minutes. Let's just take it as a warning-make sure your 1/3 pound Angus burger is just that.