My wife and I looked at a property with two separate houses on it about 2 months ago. It was officially 2 units, but unofficially 4 separate units. The listing agent was able to give us some history on the property because she was the purchasing agent for the owner in 2005.
The owner bought it for 325K in 2005. In my opinion, he didn't do any repairs over the past 12 years. Only 2/4 units are currently rented because the other two units are not livable. There is water damage which is related to structural damage.
One tenant has been there for the past 10 years and still pays her original rent of $450/month. Market rent would be $1600/month in the current condition. Maybe more with small repairs and updates. The other tenant pays $400/month for a unit with a market rent of $1200/month.
Of the two livable units, he is collecting 30% of market rent. I'm guessing the tenants made repairs to keep them livable. If you count the other two units that are at a total loss, he is collecting $850 month on what should be $4600/month across all 4 units. As a result, he is collecting 18.4% of market rent.
It's currently listed at 599K as a short sale. However, it will probably sell for 450K to 500K as a foreclosure. Why is it a short sale for 599K when he only paid 325K for it? Well, he probably borrowed against it at some point.
If the landlord kept up with normal repairs the property should be worth about $700K and rent $4600-$5000/month.