Also, you are saying gas "boilers" which implies steam radiators. 

My duplex has hot water radiators. 

They seem to think it's a tactic worthy of forming a business strategy around, to me, it's like a radiator shop saying they are in the car repair business, it's a sliver of the business.

I had 6 electric heaters just in case, sealed radiator types used a few times.

YOU have to radiate the same level of confidence your investors have to give them the comfort level that they are not going to loose their shirt with you"It's a hard tough business and you have to have a thick skin to play.

The hot water pipes leading from the boiler were leaking in 20 places the inspector could see and as a bonus were wrapped in asbestos.2) There is only one thermostat for the building so the tenants on the top floors often open their windows during the winter because so much heat comes off the radiator, as a result the gas bills (landlord payed) can sometime be more than $3000/month in the winter.3) Some of the electrical panels had been updated but most had not and the wiring was all original fabric coated and would have to be replaced if worked on.4) The roofs needed replaced.I could probably use all of this to get the price much lower but it seemed like just too big a project to take on especially when the numbers were good but not great.Any experiences working with older properties like this?

Same for the radiators if the heating system is a boiler with radiators.

There's no dishwasher, old stove, chipping paint on radiators, broken tile in the bathroom etc.

Whether you are liable or not is one thing, but whether or not you'll get sued is another.Fix the fence to minimize your liability, and leave some radiator fluid around to minimize your chances of getting sued (tongue in cheek).

One other thing to watch if your heat is delivered by radiators.