'Many questions following technical talks seem intended more to show the expertise of the questioner than to elicit information.'
I am glad I am not the only one who thought so. Lucky has a few other observations:
'The (typical) question goes something like this: “Are you aware of the work on this subject by Professor John Blutarsky at Faber College in 1962?”...“Oh, yes, that Blutarsky,” you say, playing for time. “It’s been some time since I studied his work, but I believe that his assumptions were quite different, and we all know how much technology has changed since then.”...There is an uneasy stirring as people crane their heads to view the questioner. Who is this expert who is familiar with Blutarsky, whose obviously important work the speaker seems not to know?'
There is another category of questioners: those who don't want the speaker to leave with the impression that no one was listening. So a few questions are raised about obvious drawbacks/extensions to the work, something along the lines of 'have you considered the case when k=0', or 'how will your approach do if conditions z hold'. The speaker might then explain that they were not really focusing on the k=0 problem, though with some modifications, it might be possible to get reasonable results. Of course no one really cares what those modifications might be: they are just relieved that the talk did not end in the question-free zone. That would be bad karma.
You can read Lucky's article here.