A separate Category dedicated just to scam/fraud as well as what @werkof said, possibly a hashtag available so one can easily mark/search all potential or real scams until proven otherwise. The other thing is, you probably will want to moderate that category, just so one of you can vet the submissions. We don’t want false positives (tarnishing our reputation) or rather, we want to minimize false positives.
Yes, it’s more work for you - however, if you specify a guideline/due diligence to be performed on what you want done before making (or removing) a submission, I’ll gladly follow it and/or moderate the category for you according to such clear, unambiguous instructions - or the best you can do to provide such instructions. If the moderator has ambiguity, then he can escalate for more research to someone from IOHK/CF.
Fraud, e.g. scams or other security issues are too important to ignore and deserve a category of their own.