If you fell that it's only for spamming a new topic (to get some merit in the end, I don't know why, but some newbies thinks that if they open a topic (or poll) quite frequently they will get merit sooner or later...)
So if you think that those users are only opening these kind of topics (polls) in order to gain activity, you can report it with "low quality", or "meaningless post" and mods will delete it. I know it's not the same to cure the problem instead of the prevention, but that's all you can do now.