Real Estate: Cash Flow and Sheriff Sales

[aceupthepants]

Hey guys I have been reading up on real estate and I was wondering about the pros/cons of buying a property strictly for the cash flow it produces. Take for example a particularly bad area around me where duplexes are selling for roughly 120k with each unit producing a rent of 700 totaling 1400 a month and 16800 a year. Now that seems like good cash flow but this is a bad area with a lot of drugs and other problems, so why does this seem like a good investment to me? I guess I am focused too much on the numbers and not looking at the whole picture, it just doesn’t seem to make sense to me.

Also I was wondering what the general thought on sheriff’s sales were? When a buddy explained it to me it seemed too good to be true. I noticed in the upcoming sheriff sale that a house in an area where homes sell for around 250k is going to be sold for 140k, why does this seem too good to be true?