As @Frank Maratta noted above, thorough screening can help weed out the serial wrecking-balls, but some people are always going to lash out at a perceived slight or out of frustrations that you may have nothing to do with. 

It seems that the ball is really in the tenants court.

I have made low ball offers on properties that needed a lot of time and money to get up to market price.

You don't know, unless you have a crystal ball.2.

Basically your looking at learning market research which is a whole another ball game.

They are all different.You can talk to some commercial GCs that specialize in interior fit ups to give a ball park idea of cost.

Totally different ball game up your way--almost like a different state :P I'm way south- Salem County. 

As you reduce the price, it raises the question, what is wrong with this property, which will just invite low ball offers.

My being a worry wart, would be constantly concerned if she inadvertently drops the ball because she was not aware of a particular law or statute, and I would pay the price as owner. 

I don't want to low-ball the realtor too much but they are not in a position to negotiate.