I call these "Don Norman doors". It's been 30 years since he wrote The Psychology of Everyday Things (aka POET) and people are still doing stuff like this:
But hey, they recognized the problem -- and "fixed" it with documentation. Yay?
I was recently mystified by the following control in a hotel shower:
One of those controls temperature, but it moves most of the way around so it's not clear whether you need to turn clockwise or counterclockwise. The other one controls which of two different shower heads to dispense water through. Why there are two shower heads is left as an exercise for the user, I guess. (And, of course, when I'm trying to operate a shower, I don't have my glasses on.)
(There's lots of discussion of affordances in general and shower knobs in particular in the comments.)