Okay, maybe there are dumb questions.
Questions asked because you were not paying attention.
Questions asked about topics your job requires you to know.
Questions asked because you are too lazy to look up the answer on your own.
But even then, are they really dumb?
Stupid is another word for dumb. Just as lovely as it is for you to read as it is to write, but it's true. The definition for stupid is having or showing a great lack of intelligence or common sense. I guess that means that a dumb question shows a lack of intelligence. But is that not the point of a question? To fill our gaps in knowledge, to be less dumb? Even if you should have listened, or you should know, the fact is, there's a gap.
Does that make all questions dumb questions?