I can look to see if there are bars on windows, graffiti everywhere, how well people care for their lawns, etc.

If well coordinated, at a minimum that provides 30-90 days without being responsible for the mortgage payment.Investors exploring this strategy will want to emphasize efficiency and be sensitive to PPP (Pre Payment Penalties.)

There is a legal doctrine known as "adverse possession" by which trespassers who openly inhabit and improve a piece of property that is otherwise abandoned may gain title to that property after some specific conditions are met.

We freshened up the interior with new paint, and a few new trim items, but mostly it was well landscaped and well cared for prior to our assuming the loan on it.

With this support system in place, you'll be well-positioned to tackle a flip down the line.

Examine the possibility of future value growth for the property as well as any tax advantages that come with owning rental property.

This can help make sure preventative maintenance as well as minor things don't cost you as much as a handyman visit.

It's true you get a tax deduction for your mortgage, but you also pay taxes on whatever else you decide to do with that money.I would list all of your known investment opportunities, what you think the after tax returns would be, and a risk level 1-5.If paying the mortgage is a clear standout on that list on a risk/reward basis, I would spread out the $60k over a period of time and apply it to principal.You might have other goals like cashflow or reducing risk which might weight towards paydown also.

Agree with all the points Ty has already made above as well. 

Quote from @Caroline Gerardo: Well allowing ninety days to pass without clear oversight is a disaster.Where do you live?