I told him that he could buy my book (all profits are donated to Junior Achievement),2.

As prospective college students and their parents start to wake up to the student loan scam and online education becomes more accessible, not only will the loan "bubble" pop, but the traditional 4-year on-campus college "experience" may become a thing of the past altogether.Since the economy in many college towns is almost 100% reliant on the University (and thus government & private loan programs, donations, etc.), any downturn in that corner of the economy will drastically affect your rental business.

Then the best case scenario is that your girlfriend is donating $10,000 to a charity case. 

The only thing that you could consider "donated" is the advice and time of the hosts.

She lives off food bank donations. 

If you are not former military etc you can make a donation to a charity to join.

I might even forgive a debt on occasion for a good tenant that is going through a personal struggle though I'll never donate to the united way.

The turnover, unexpected vacancy, deception, numerous inevitable repairs, evictions, overall chaos will make it very challenging  one of my bizz partners did just that bought in the bottom of the trough.. for 100 to 12k each .. had to put 40 to 60k each to get them habitable.. he finally gave up and donated them to his foundation.. 

MLS - negotiated with investor to include the kitchen cabinets (ended up donating them) they had bought along with appliances How did you finance this deal?

I now want to donate the fully depreciated asset to charity while keeping the passive loss from the depreciation.