Annoying?
In some cases, the thread is so old that they have become irrelevant, yet what you want to talk about about is still related. Would it be a better idea to just start a new thread?
What annoys me is when a newbie bumps a super-old thread to "talk to" people who are long gone. If they dredge up a thread to add new information, or update their own thread, it's not so bad. And if it's to ask a related question, it should only be if they did their best to search for it first.
