I think investing in IEO will reduce the chances of being cheated to zero percent. But yes you have to choose the trusted and popular cryptocurrency exchange market to do IEO.
NB: No one is being encouraged to invest in the cryptocurrency market here. The information is only for those who trade cryptocurrencies at their own risk.
IEO was conceptualized because good and legit projects cannot move and get funded because of the lack investors unbelief of ICO, so many investors have been scammed by ICO that investors have stopped looking on ICO for a new coin to invest, IEO is a big help to connect projects and investors, and it's a win win situation to all, just be sure to pick the project that will go a long term.
IEO and ICO is still both equally scammy in my eye, just because it is done by an exchange doesn't mean that project owners will not turn out to be scammers. Sure there is a bigger chance of scam in ICO world and I would still stay away from investing into an ICO unless it is done by someone I know and like personally, but same goes for IEO as well. I am going to make up some numbers but let's say only 10% of all ICO's are profitable in a year and only 20% of IEO's are profitable, that still means there is a low chance on IEO even though it is a higher chance.
Numbers are made up but that is how I look at it, just because it is better than ICO doesn't equal it to being good at all. Hence no matter what the offering system is, I do not invest unless I really believe into it.