Based off my experience and my success in Detroit-
Detroit Michigan is one of the best cities to invest in, HOWEVER, it is imperative that you have the right team on place and a good understanding of the marketplace.
It's true that there are a lot of out of state/country investors that get taken advantage of due to the lack of knowledge and team guiding them. The reality is Detroit is a block by block market filled with values that scatter all over the place along with problems that arise as they would in any other marketplace.
I think the issue is people that sell your properties in Detroit glorify the returns and fail to explain the risks associated with investing in such markets along with the actual values of these homes. I think if most investors understood the whole picture before buying in the city - it would avoid a lot of headaches for said investors.
For the scams, and misrepresentation - it is true, it happens, but it also happens in a lot of other cities, and it really comes down to you doing your due diligence in who you work with.
Regardless, do not let any of this discourage you - if you find the right team - Detroit can be a great place to start and grow a portfolio that generates solid returns.