I hate generalization, this is more like saying all altcoins are scam or shitcoins or more like saying, every post made in the altcoins or bitcoin discussion board are spam just because more spam are made in those boards. I have read story of bitcoin signature scamming their participants too (project not paying their participants for promoting them). No type of campaign is safe from scam therefore you just have to be conscious when joining a campaign.  Be very vigilant when joining a campaign, note that there isn't any guarantee to get paid so don't invest all your mind and body into a project.