This forum has the scam accusation section for such purposes. There are many threads with ongoing investigations of projects as well as proven scams. I think a thread where people would put all of them is inconvenient, but perhaps is would be good to make a childboard in mate section, devoted specifically to ICO scam.
Unfortunately, scam is always out there when there's a free market where nobody is forbidden to promote one's project.
I suppose a way of dealing with this situation would be to make some additional forum rules on promoting ICOs. For example, for ICO to have an ANN thread, make sig campaigns, bounties and airdrops, it would need to have:
- official website
- a team, whitepaper and a roadmap on the official website
- an escrow for any things related to paying people some money in btc.
But this wouldn't stop the scam projects anyway, it would just prevent forum members from investing in them.