We often get calls from homeowners and not ones that want to sell us their home, they want us to buy the neighborhood eye-sore!
Now, there may be several personal motives behind that call but the fact is when you go to sell your home, the neighborhood has an effect on its value. It may not show up on paper but when potential sellers come by for a showing and see a disaster next door, it can easily effect their decision.
More often then not, the owner of that mess of a property doesn't even live there. It could be an unwanted inheritance or even a mismanaged investment property that ended up condemned. However in either case, your houses appeal can be curbed by the house right next to it.