Really ?
I mean I am not a prophet or a fortune tellers but I think that most people would come to the causal chain that if they submit a spam or joke-proposal their reputation would be spoiled a lot with the downvotes they receive ... I guess you would not like if your reputation fall under 0 cause you had submitted such a propoal isn't it ?
So it would be just a try how many people here really care about destroying their reputation just for fun.