The refrigerator always seems to have some gross stinky mystery stain that requires deodorizing and scrubbing.

Door knocking, direct mail, cold calling (be sure to scrub on DNC list), cold texting (check regulation on this as well)...all methods will work if you are persistent and do enough.

Propstream does skip tracing, but they do not scrub against DNC/ligation list.

Chances are unless you have a good system in scrubbing your lists, you are already 'dripping' to them.

Just a matter of weight it up and costs associated with this.Alternatively,  start scrubbing, get the sucker pristine ... just joking.Seriously if you have a great tenant and pays on time, just bump the rent up on next lease renewal to cover costs.... win/win

In the past we have used scrubbing bubbles to clean the walls.  

If you don't feel like getting into a lawsuit you should scrub against the DNC and known litigator list. you might not technically be "telemarketing" but lawsuits have been going wild lately.

I believe there's even existing software that code enforcement agencies are using to scrub listings and identify illegal ones more easily now too.

As everyone else has said, definitely clean first (light scrub with soap and water and large sponge). 

All it does is scrub public records to find lender's who are not entities.