I guess they did not clean the unit for over 3 years and did not call the old property management company when things started to break. 

Also if you have a clean unit the new owner will be excited about the idea of renewing your lease. 

Hi, I just got into a fourplex property and found living room has a sagging floor.

A: "YES, PLEASE FIX THE SHOWER"A: "yeah ever since my landlord was tiling the shower and put some grout mixture down the drain we've been having consistent drain backups (2nd floor!)"

Refinished hardwood floor underneath.

Can they be cleaned enough or is it replacement only?

I have seen it for whatever reason and it's not an absolute, but my A class tenants when they move the houses ARE broom clean and they get their deposit back. my C and D needs a turnover which usually cost 1 to 5k depending on how rough they were on the houses.

If you have carpet consider a cleaning clause if you don't have one. 

I recommend "bulletproofing" your property if any updates need to be made, such as waterproof luxury vinyl flooring. 

(Increased rates and loss of discounts on all policies, not just this one.)You’d be better off raising all your deductibles and using the savings to pay for your floor repair.