The Cheese Test (youtube link) is a great way to visualize this. If the food doesn't rotate, you end up with hot and cold spots.
(This was just the first video I could find of someone performing the test for people who hadn't heard of it, I didn't listen to the video, only confirm that that's what they're doing)
The people who talk shit about clowns are the people who wouldn't survive 2 weeks in clown college, which is a real thing you have to go to to be included in the World Clown Association. Clowning is a ~~serious~~ real job that people don't give enough respect to.