I don't think most of them, otherwise we see a widespread of IEO now.
Based on what I read about ICO, majority of it is scam, so they will not pass in IEO as I believe there's a certain requirement for a project to be in IEO and the exchange will certain do some investigation on the project you are offering, if they find it not worth enough, they'll not risk backing you.
So for that, IEO is the best for investing everyone and seeing what markets they have entered when holding the IEO, maybe from that market you can determine whether it is good and you can judge for yourself.