Vacant as in blighted, abandoned, condemned, infested, etc.

And considering that PA is infested with slumlords and gullible students and internationals willing to pay for high market rates for low quality like in NYC (without the NYC opportunities or amenities), it's not surprising that Sec 8 is simply not as popular here. 

Trash and rat infested backyard.

Here in Georgia, termites are very prolific and most houses that have been around a while have some infestation history.

She has lived in the house up until the past year but is now renting an apartment cuz it is infested with rats.

The rental and foreclosure is hot where I am, though that could be the same for you as well.I've consulted a few investors here locally and their idea of "helping me get started" was to sell me 3 run down rental houses in gang infested neighborhoods as a package deal for 32k.

A house is a liability generating asset. Be a responsible landlord and do everything you can to limit your exposure.

Largest award ever in similar lawsuits against Landlords:

http://realestate.aol.com/blog/on/faik...

I found a six residential unit + 1 commerial commerical unit which has a recent infestation of cockroaches.

We have a house that we are rehabbing and it has an African Killer Bee infestation in the attic.

Depending on the age of the building these could range from dryrot, pest infestation and mold to serious structural defects, plumbing and wiring issues.