In any case, IEO is a more promising investment. Scammers are not interested in their coin or token developing. Really serious projects pay a lot of money for IEO.
You may not know because there are scammers too that are willing to invest just to get in to this new way of investing and funding of such projects. If they had the money to invest to be considered by these exchanges to run an IEO, well it is possible for them as long as they have money.