As stated in the topic, what is the first thing that makes you raise the alarm?
Bunch of things,
-> Self Moderated Threads + several bounty campaigns with a broken English speaking campaign manager.
-> ICO appearing out of the blue moon with a non-newbie account with a team that is hired from bitcointalk.
-> Cheap ICO page with a bought script and a bootstrap theme.
-> Another POs shitcoin with no creative idea behind.