It really depends on the thread. Usually I don't have any problem with reviving old threads if it is, for example, an old sales or hangout thread of yours or a support or feedback thread you want to add your opinion too. Usually I am fine with most threads being revived, as long as it does not happen in a spammy kind of way - like a user going through the chat forum posting in 20 threads that were several years old just for the sake of gaining food, or posting in old Newbie Welcome forum threads where the users have registered months or years ago and never even came back after that and so on.