Lots of good advice here, thank you all. I've always wondered about these types of houses. A friend's new BF has his own business maintaining homes that the banks have taken over. In some cases, they just need some curb appeal, in others, the wiring/plumbing's been gutted or the owners walked their dog inside the house before leaving. (ewwww)
If you do buy a house that's been vacant for a while, take my advice and have the sewer main snaked out before you move in. It's a worthwhile investment - we had the main back up after 2 hours of cleaning into the basement. What a mess! Everyone we know that's been in the same situation and ignored our advice ended up with a mess when the same thing happened to them.
There have been construction guys there ever since. They tore out an entire semi-trailer-sized dumpster of drywall / pink insulation, what looked like half the interior doors, and a couple toilets, in addition to taking out and boarding over the kitchen bay window. We're guessing water leaks in the bathrooms + being closed up in the heat = mold necessitating the removal of all porous surfaces.
You never know what you're going to get.
Could be unseen damage, but it could also be clever renovators or "house flippers."
It's so much easier to do renovations before you move in. When we bought our current house, we had all of the messy work (running electrical lines, replacing countertops, tiling) done before we moved in. Maybe the owners wanted to update the kitchen and bathrooms now instead of when they go to sell the house.
We saw a similar situation - tiny cottage that backed up to a park. It was in good shape, but had been vacant for a while. The new owners bought it for a decent price, but never moved in. The neighbors were nervous that it was vacant for so long.
The buyers completely gutted the place except for one interior wall. The cottage became a McMansion. They used a home improvement loan to finance the deal, but everything except that wall was brand-new construction.
They ended up with a huge house on a park worth many times what they paid for it initially.