Leaving aside the endlessly repetitive questions such as:
* Which arrondissement is the best to stay in?
* Can you recommend a good hotel?
* How do I get from the airport to my hotel?
* What will the weather be like?
* What should I wear?
and all the rest, all of which could be narrowed down to something meaningful, if not completely answered by a simple search...
What annoys me more than all the above is the amazingly large number of posters who ask a question, get at least one detailed answer (and sometimes several) that took time to compose and may have taken at least a few minutes research, and who never even acknowledge that they have read the response, far less take the five seconds to type a thank you.
Given that the vast majority of posters on these forums are American, is it any wonder that US visitors to Paris (and many other places) have acquired a reputation for being impolite?
Not that this is a universal thing, I hasten to add. Some posters graciously acknowledge the help they have recived. IMO there are far too many who do not.
Rant mode off...