Yeah that would drive me insane to run across. It’s not even particularly hard to tell that the exhaust fan motor is reversible just by looking at the top/back of the microwave before it is installed. Every one I’ve seen looks pretty damn modular in comparison to the rest of the microwave shell.

Edit: reversible is the wrong word, able to be unscrewed and rotated, I’m sure you know what I meant but on a reread of my comment I wanted to clarify.