I definitely think that there is such a thing as a stupid question. I think that a lot of people tend to ask stupid questions due to being lazy and ignorant. But I do think that sometimes asking a stupid question enables some people to never ask it again. I think that people should just be more smarter.
Unless a stupid question is asked out of real, genuine ignorance by a person who can't possibly know any better, then yes, it's stupid. I never understood this saying. Not all questions are there to seek out knowledge. Some are just offensive or can be answered with basic instinct or common sense.
Yes, there is such a thing as a stupid question, because people need to learn to think for themselves rather than asking too many questions right away. Also, if the person was listening to begin with, it is possible that the person giving the lecture already answered the question, and they just missed it.
I believe there is such a thing as a stupid question. Last week I saw a few questions on here that essentially asked if a set of buildings was inherently evil. They were referring to an actual government, but they used terminology that didn't fit in the question or they failed to understand the terminology. Questions can contain false information just as much as answers can. If your question doesn't make any real sense, then it can certainly be considered stupid.
There are no such thing has a stupid questions just stupid people who ask the questions. And some times stupid question can be good questions like: Why is the sky blue? It seems like a stupid question but it is really not. Remember there are no stupid questions just stupid people who ask them.