It seems with prices now this is the only way to get cash flow while accounting for the items mentioned above by Joe Fairless.

Between these two you can find a lot of items. 

I have a clause in my lease that says all money received is used to first pay outstanding items like fees and utilities and then money is allocated to rent.

It does however damage some materials but is worth it to get rid of smoke odors and shouldn't damage too many items.

I am getting ready to start a rehab project and I remember reading somewhere where you can take a list of your construction items to the PRO desk at both Menards and Lowes and they can send them up to corporate for re-pricing. 

(A Security Deed transfers an ownership interest to the Bank in order to Secure their interest in the property—an analogy is a car title where you and the Bank own the secured item together).

Make sure they itemize their receipts.

Some only cash flow about $125 per month so if I have really 1 maintenance item I am at break even or zero cash flow and if I have more then 1 vacancy I am nervous.  

This can be a pricey item that your lender (aka seller) might be willing to forego.You would still have the other fees associated with buying the property, mostly title company related fees.

We never want to be caught with the wrong date postmarked on the envelope, so we prefer to go to the counter and we go the extra mile by getting a "Certificate of Mailing" that proves the date the item was mailed.