Sketchy addition on back of house

[Bienes Raices]

This house was a 2/1, but there is a sliding glass door in back, where owner put on a very small addition with a half bath. Floor appears to have a very slight slope, and roof shakes a little bit when you walk around in the room. Room is only about 80 square feet in size. Rest of house is concrete block, but the addition looks more like a manufactured house in terms of materials. A permit was not pulled for the room.

My options are:

1) keep room, advertise the rental as a 2/1 + bonus room.
2) go ahead with deal, but pay to have the addition demolished
3) back out of deal

I was wondering what others would do in this situation.