Unless you have some way of controlling what people report as spam ideas, every idea will be reported as spam. People have different ideas about what constitutes a crap submission and then some will try to get their competition removed. Either way, it’s a bunch of unnecessary work for whoever would receive these reports when there’s already a mechanism in place for getting rid of spam: the downvote bumon. And if you really don’t like one submission, bring it up on the forum and I’m sure you can get a bunch of fast downvotes.