As an investor, i cannot participate in IEO conducted by small and new exchanges. The main reason why IEOs are preferred to ICOs is because they are more prone to scam than ICOs, and this is because the exchange validates its legality with their reputation. Imagine Binance or any top exchange conducting a scam project, it will jeopardize their integrity, and these exchanges do not want their integrity in question, so they only offer legit and promising projects IEO. New exchanges do not have the reputation to validate a project, they are just after the profit, SO they might promote a scam project either intentionally or unintentionally.
Maybe it's not intentional to promote a scam project of this exchanges and I think they search all details of the project before thay accept or launch in their exchange. Of course they want to maintain what people see to their exchange, so they be sure every project that they introduce in the people. If that project turns to scam its not the fault of exchange and I think they will kick immediately that project if they will discover that project is suspicious doing.