If the source is electric, it must be permanently installed and controlled by a separate thermostat.If the downspouts or gutters are damaged and/or missing, causing interior damage of the unit, they must be replaced or repaired.

And budget for storm damage too.

I'd also assume tenants there do a lot of damage so you could end up paying 20-50k in renovations each time you turn the property over unless you have a good handyman.

A couple of things I thought about:-confirm smoke alarm operation and fire extinguisher charge-no damage to unit-change furnace filter-check all drains for proper drainage (clean out traps if needed)Thanks in advance! 

Recently tenant contacted me, pipe backed up, sewage into house, damaging original wood floors beyond repair. 

They will find minor things and consider them violations, even if the tenant did the damage.

Isn't this very expensive repair restoring the property to its previous condition?

The landlord came by to check out the room after I moved out, no damage whatsoever, well, I was there for like 4 months only.

If there is any damage due to tenant abuse, the tenant must pay for the repairs or lose their voucher. 

Contact an attorney and have them send a demand letter for damages and breach of contract.