Yes it could be. You can trust anything in this space. Normally ieos are in big exchanges is very rare chance to be scams. But in mid and small exchange which ieos are offered can be scammed.
Is the ticket system IEO in big exchange can qualified as an IEO ? Since the one who get the coins is the one who has lot of balance and lot of luck.
I think the exclusivity of the coin make the price going high