They say that but honestly it’s easiest to just spray hot water on the top and pot (with top off) once you are done popping and it has cooled down a bit. That way you don’t warp the pot. The gears get gummy, but as long as you have the metal ones, they hold up well. I have one older one with the nylon gears that is nearly stripped. Whirley-Pop sells replacements in the metal version.
I actually don’t like to use soap on it because it develops a bit of a seasoned inside after a pop or two and makes it easier to clean when that time does come.
If you pop anything sweetened or with sugars, clean it EVERY use.
If you pop normal batches and will reuse it again soon, you can go 2-3 popping sessions with not much but a wipe down.