The number of scammers will grow. That's unavoidable. Especially now, when the countries start to ban ICOs.
To protect yourself you need to learn how to make really good researches on upcoming ICOs.
To protect the others - simply inform other investors (for example here on forum) if you have found that the ICO is going to be a scam. Make sure to provide some evidence of your research to make sure you don't call just every ICO a scam.