Don't know. I suspect a house of people heavy into the occult would be rather creepy, maybe black paint in some areas, other signs. I guess we just take our chances when we buy a house. Can always have a priest come out and inspect the place, perform a blessing over the house, cast out any bad spirits. When I bought my house the owners seemed pretty normal so I did not even think of occult and such.
You could always pray over the house for yourself, right? Do you need a priest to come out?
Questions often create more follow-on questions than might be expected. In your example here, how "heavy into the occult" is acceptable to you before you decide not to bother? Would you buy from an estate sale, when the house was emptied and you can't tell whether or not the previous occupant was a witch? How many owners have to own the house between an occultist and you before you don't worry about it any more?
Black paint doesn't really prove anything. Lots of black could just be indicative someone into the goth/emo movement, especially if the family has (or had) teenage children.
It sounds like ultimately the question of whether a house had been used to practise the occult comes back to whether you get a bad vibe from the place. If you get a bad vibe it sounds like the kind of thing where the house just doesn't feel very "homely" to you, in which case it probably doesn't matter whether it's because of some dark occult past associated with the house or because you just don't happen to like the place much.
