The [nice?] thing about them is, with the unit at the top pushing air down all the time, the lower you get the more you have to clean.
The white part on the bottom just keeps it in place on your counter. It is external to the part where the food is held, just dust/clean like you would any countertop machine.
There is a glass dish base. It's about as big around as a pizza and about 3 inches deep. It nests in the white base and is separate from the top part completely. Most of your 'mess' will pool down in the bottom of this, and you wash it like you would any large platter.
There are various stainless steel racks you can mix and match that go inside to hold the food. Obviously, since they are in direct contact with the food, they need regular cleaning as well. Think of like a BBQ grill the size and shape of a pizza pan with little legs on the bottom. Since they're stainless steel they reliably clean up with soap/water and will take elbow grease if anything gets cooked on good.
The clear top shell comes loose from the white heating unit on top. You just twist it 25-30 degrees and it pops off. It's a little more cumbersome to clean due to its size, but since it's higher up and the sides are vertical, you don't have to clean it every single time. After a while the oils and such start to make it cloudy to see through and you'll want to take it off and clean.
The white unit at the top you'll hardly ever have to clean. Unless you cooking something like a fatty brisket or foods with sauces that will splash up there, you can go months or years and it will stay clean enough to use. There's a mesh guard you can remove to soak that protects the heating element, and at some point, you may use it enough you have to remove the fan and soak it as well, but this is a rare thing. Obviously you can clean the exterior like you would your toaster or coffee maker exterior.
The top part looks like this when separated from the base.
