There was actually a story here in Phoenix about a house where I think a father murdered his wife and three kids. It was apparently a very gruesome crime. The house was put on the market, and as required, the buyer was notified of the murder. Well.. unfortunately, the buyer decided to rent the house and didn't tell anyone of the murders. These other people moved in and about a month later, neighbors said something about not believing how brave they were to live in a house where 4 people were murdered. The tenants freaked out and demanded a lease break. I think they got it because of laws requiring even renters to notify potential tenants, but it was still disturbing that the guy didn't tell anyone!
Personally if I bought a house and found out later that people had be murdered there, I don't think it would bother me. I really doubt, however, that I would move into a house I already knew had a murder happen in it. Seems weird, but I guess once I already lived there and made it homey, it probably wouldn't bother me.