Hidden Problems in too-good-to-be-true Properties

[Alexander V.]

Hello, this is my first post on the forums, and I'm in need of some advice.

I've been analyzing potential properties for about an hour per day for a while now, just trying to get a feel for analyses and markets. I've noticed that in some markets, it seems impossible to find a property in which the numbers work; however, in others, it seems like almost every property looks good on paper. Specifically, I've noticed that Cleveland OH has dozens of duplexes for under 100k renting for $600-$900/month/unit, even in some of the lower crime neighborhoods on the west side.

When every deal looks good, I know something is wrong, but I'm too new to see what it is. The biggest issue that I can see is that almost without fail, the small multi-family homes in Cleveland are 80-120 years old, and I'm unsure of how to accurately estimate repair costs and hidden expenses. If the repairs are 10k (as some of the sellers claim...), half of these properties would have a CoCROI of 30%+ with a conventional loan at 20% down, which is possible for a home-run deal but clearly not for just about every duplex on the market. So what are the potential issues that make these on-paper good deals in-reality bad deals?

For a couple examples:

https://www.realtor.com/realestateandhomes-detail/...

https://www.realtor.com/realestateandhomes-detail/...