At least drain & flush the tank (Be sure to crack open one of the fittings while draining to allow air in).

When you are buying from individuals you can flush them out on the phone. 

I have had loans where I was in this situations before and what I finds that works is this.Call the first and see what's upLook for Lis Pendens from the firstIf no Lis Pendens send a demand letter and wait 10 days, if no responseBegin to forecloseThis will flush out the borrowerIf still no response, take the property with the first and rent it to recapitalize or hold for investment after a short sale.There is always a way to make lemonade from a lemon.

I was flush with cash at the time and I didn't want to rent. 

Another thought , readjust the toilet to use more water per flush , you may not be getting enough head to push the load thru . 

"Meanwhile foreclosure starts in July were at the lowest level since November 2005 — a nearly 10-year low that demonstrates the recent rise in bank repossessions and represents banks flushing out old distress rather than new distress being pushed into the pipeline."

What it does is stops the fill valve from running without an active flush.

Indoor I have cleaned area(if non structural) applied either wood filler or mud with plaster to harden, sand to flush, then prime and paint.Same thing for exterior non structural areas of smaller size. 

"Why should I pay , the wipes say you can flush them "      So I tell her that the lease says that clogs caused by the tenant are the tenants responsibility .Her reply  "  nobody ever reads the lease " I called the tenant , he told her to go home , and if he cant clear it , he will pay to snake it . 

Bob here is a thread which flushed out many misconceptions of CFD's from a little while back.