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.
Indeed, not all IEOs have great profit, and not all listed on the project are legit or profitable. There's no east or absolute way of earning a lot because the market is as dynamic as it is. IEOs could help or further ruin the reputation of the industry but of course I hope it is the former. Any playform could promote a scam project so putting the trust in the platform is the risk that investors must take if they want to participate in this new trend in the market.