I do not go looking for fights but am comfortable dealing with conflict if need be.

Fight that $ amount for sure.First step, get each unpaid bill and then get the most recent paid bill by the tenant and check the meter readings. 

Police calls, fights, arguments, code enforcement calls, plus a poor history of paying on time, increased evictions and lack of care for the property in general.For your own sanity, I encourage you to add “Don’t” to the list of D words above.  

I am not employed by BP and have no dog in this fight other than to shine a spotlight on the exact website you are posting in to seek your "diamonds" looking for answers.

A lot of A/ B housing tenants will fight like hell to avoid C class housing.

As far as the lighting, if you strongly feel there may be some issues there you can also request that the seller pay for an electrician to come in an check the place out as well.I don't think the seller would fight this too much since it is totally reasonable.

They have basically committed to spending $50,000 to fight it, with an eye to making the wholesaler pay more than them to win the case.The truth is that there is a lot of money in real estate, but not always a lot of profits. 

If enough people started fighting it, I would imagine that it wouldn't be terribly difficult to overturn, but you would need the support. 

He also didn't give a full 30 days notice, I'm not going to take his full deposit, but because he didn't give 30 days would that forfeit his right to the security deposit if he tried to fight the cleaning fee?

However, keep fighting it and see if others in your city have had a similar problem.