I often buy using Subject To to buy properties. If you choose to use this technique these are some of the Pitfalls to watch out for.
Subject To Pitfalls
1. The bank can call the loan due (due on sale cause).
2. You...

But it’s quick!

You can do some quick research on Lowes or Home Depot website and easily confirm that you can buy a water heater for as little as $400 up to $1200.

I've been able to fill my vacancies relatively quickly compared to my duplexes in the same neighborhoods. 3.

However, i never expected it to appreciate so quickly.

A quick Google search should bring one up.

You get the most favorable financing, your down payment is much lower than a rental, you can therefore afford a more desirable asset which mitigates risk (nicer properties appreciate more, are easier to sell, attract quality tenants and have lower vacancy/turnover), you will learn the ropes without nearly as much risk as an OOS property presents.

I use a version of the 50% rule as a quick but reliable measure of expenses on a single-family: you can reasonably expect all monthly expenses not related to the  principal+interest of the loan on a property OVER THE LONG HAUL to be 50% of monthly gross income.I also think she's just calculating that PITI expenses are pushing her down to - $120 a month.

I hope Mario can mitigage his losses by selling the property quickly to stop the bleeding, or re-tenant and refinance to less expensive debt but this serves as a case study on the perils of investing in lower tier neighborhoods.The amount of people on the internet and social media selling the false narrative of how easy it is to create wealth through investing in real estate, specifically these lower tier neighborhoods is upsetting. 

In these instances you should ask yourself what type of tenant you want to attract.