My house is a modest townhouse built in the mid-70s. I'm the second owner, and when I moved in there was a built-in 8-track player in the basement!
I have no indication that the previous owners had a clue about the problems that were in the offing. I had the house inspected before I bought it and it got a clean bill of health--the problems started a couple of years after I moved in. I don't think the previous owners know how lucky they really were!