I did a walkthrough before closing and there was a bunch of junk still in the garage (numerous paint cans - some that were very old, an old microwave, and old door, cut drywall, half a bag of grout, and some other junk). 

There is a tool they sell at the big box stores like HD that you attach a small plastic bag to (like you get every time you go to the store).

I'm thinking there are some things that everyone should do if they can to prepare and be in better position to continue investing no matter what happens: build up cash reserves, focus on buy and holds or very high velocity flips so you don't get stuck holding the bag if prices drop, etc.Any suggestions?

Does it make it enforceable: NO.Unless you use some authentication in the chain of signature where it can be traced to a certificate that has been verified as owned by the person in question, these websites are useless. 

Have you ever looked into the dumpster "bags" if they have those in your area?

Mark, you are missing a key piece of info the owner has let out of the bag: she wants to get out in her RV!

He also used to rehab and flip before the market crashed, although the one strike against him is that he found himself holding the bag at that point.

You are ultimately the responsible party, and will be left holding the bag.

GlenI have a couple of properties in Longview, it can be a mixed bag in terms of neighborhood quality and rental rates, so do your research.

Which brings me to my next love, which are contractor demo bags.