How do I know when I have a worthwhile deal?

[Terrance Merck]

Situation- I am currently looking at a two bed 1 bath that is in pretty good condition. As of 2013 it was valued at $28000. In 2012 it was valued at $50000. I was looking at this property for wholesale purpose. I am not sure if there is a deal here and would like to know what others think and if is so how should I approach.

I haven't contacted the seller. Just gathering Intel and trying to weed out before moving forward.

All perspectives are welcome,

Thanks in advance