I guess the best way to avoid ICO scam is not to invest in ICOs at all   That's the only way to be sure. And it is not really as bad as it sounds. One may still explore the ICOs which seem interesting and invest in them when the coins are released. I think that mostly the prices don't differ much from what they used to be during ico when the coins start to appear on exchanges, whereas the safety obviously grows a lot since you can be sure you'll be able to sell the coins just as you were able to buy them.