I am taking it as getting to know what I believe fits me and my circumstances. 

FEDERAL TAX LAWS; (B) SUCH DISCUSSION IS WRITTEN TO SUPPORT THE PROMOTION OR MARKETING BY THE COMPANY OF THE TRANSACTIONS OR MATTERS ADDRESSED HEREIN; AND (C) PROSPECTIVE INVESTORS SHOULD SEEK ADVICE BASED ON THEIR PARTICULAR CIRCUMSTANCES FROM AN INDEPENDENT TAX ADVISOR.

It just depends on your circumstances.

Make sure to have a reserve acct set up with your sister for the unforeseen, and have it owned, most likely in an LLC, so it clearly spells out your roles, and ownership %.  

While the 20-25% cap rate properties look appealing, it masks the problems associated with buying a property so cheaply (Unforeseen maintenance costs, tenant turn over, and etc).

And by CITY, I am NOT talking about small towns, I would never look at any city under 10,000 population, except for very unique circumstances..While it is getting more difficult to find deals, there are still many deals out there, and EVERY WHERE! 

@Christopher Rogers  I think it depends on your circumstances and risk tolerance.

While you feel sympathy for their circumstances, you can also look at it as that they were taking some advantage of your parents' kindness, no matter how nice they are, knowing they were paying so much less than they should, and you should be able to decide what charities you want to contribute to, not feel forced to contribute to them.  

It could be less than that but she'll never go wrong with saying 2% barring some extenuating circumstances.

So I think it is possible under the right circumstances, but only once you reach a certain scale.