They probably won't pay it, but maybe they will at least clean up after themselves.

If you're going the umbrella insurance route, perhaps see if it will cover you for several things including just the routine slip and fall (like mold or earthquake).

We cleaned them out and rented them as storage units. 

The floor needs a cleaning -- but next - should I sand the floors and then put a varnish on them?

I started out flipping and then transitioned my business to wholesaling so I can easily close on any transaction if I have to.I don't like the bad reputation that wholesaling has because of people jumping into it with no idea or understanding of best practices, but hopefully, with regulations, we can clean out the bad ones.

Deegan and @Arda Bircan There are technically 7 Tests for Material Participation (but 3 that are most common) -> the individual 500 hour mark, that the activity of the individual is substantially all, and that the individual participates more than 100 hours + no-one else spends more time than them.Litmus Test: Are your hours integral to the operationsThe hours that qualify must be substantially all hours and have a legitimate impact on the rental activities.Activities that generally count: showing the property for rent, taking tenant applications & screening tenants, preparing & negotiating leases, cleaning & preparing the units for rent, repairs, and improvements, managing the construction, purchasing supplies & materials, inspecting the property, responding to tenant complaints & inquiries, collecting & depositing rents, evicting tenants, writing & placing advertisements, and working on your websiteActivities that don't count: education & research, investor-type activities, and travel time..

To even counter with an offer of $2 is too much for the amount of filth I would need to clean out.

Not asking you to dog on your listing, but I'm interested, because I do see the middle-of-the-road homes -- clean, but not updated, nothing special -- sitting for longer and the nicer ones with a little something extra going quickly.

Find a deal, close, clean it up and get it ready to flip, and market it to investors. 

Let's say they spend 20 hours a month on marketing, phone calls, maintenance coordination, cleaning coordination, tenant complaints, or whatever.