Stupidly high soft/hard caps
Issuing massive amount of bounty rewards which devalues it for the next couple of months due to dumps
Poor communications from team prior or immediately afterwards
ICOs that don't take security serious and end up getting hacked or leaking private data like email addresses
Meme based ICOs
The distribution of bounties in their coin is a big mistake on their part, they need to give bitcoin instead, and the reason for that is that most people do not believe in the coin and as such when the coin hits the exchanges everyone is going to sell as fast as they can crashing the price of the coin.
Bounty is only 1-3 percent of cap. They can't do nothing. But big bonuses for 'strategic' investors when they dump at first possible moment all tokens at price lower then ICO price is worst.