I do not think that this is possible. A bot will not be able to read the thread and thus determine if the campaign is open or not. New members doing might be because of ignorance or not being aware about the rules. So far as senior members doing this is concerned, only reason i can think of it is a purchased account and they are not experienced with the rules of the signature campaign. The seller might be selling these accounts with promises that you will get accepted in campaigns and so they keep applying in all open campaigns.