I think IEO cheating can only happen in small exchanges but not in with highly credible and high standards like Binance, Okex , Bittrex. If ICO can cheat their collected or raised money then they cannot do it on those top tier exchanges. When IEO became a very successful token sale then that means people trust so you should try investing on it.
I see this becoming very common with smaller exchanges later in future if we dont quickly control it, exchanges that has not succeed in managing to get volume on their own platform might also be looking for IEO projects and they will end up going away with any project money they generate since they are the ones collecting the fund directly.
It will be a safe thing to do if we just be with these top exchanges, although they are not saint too but they are still better. In selecting top exchanges, we have to be picky also, since not all top exchanges got to the top genuinely,some faked their volume to get to the top and same way they might fake IEO projects for investment.