"Ask things like "If I didn't know how to read, could I still find my way around this interface?". Clearly, this is too low a bar to effectively use some applications, but simply trying to aim in that direction over and over can help evaporate the more "clever" concepts in favor of your less skilled users."

This is very useful for people who are developing UX/UIs for the older population.

A quickly growing segment where a lot of the users want to do things like use tech to keep in touch with their families and grandkids from a nursing home and they may not be as sharp as the average user of tech products...