However, I know there are always unexpected pitfalls, and there are people on here far more experienced than myself in the realm of investing.

2 things by using a space heater the regular thermostat is not registering the proper temp in a room,, or by using the stove,, the stove is a fire hazard and by no means should be used for heating.. who's paying for the fuel to heat or run the stove.. just plain wasted energyGet rid of her, let her out of lease all, she's accident waiting to happen and write her up for not properly using appliances,, NO space heater should be used in your lease,, that alone unattended is a fire hazard.You will never satisfy her

However, I do agree with you that if you do not have a solid income vacancies and unexpected repairs can be a major issue. 

There were some unexpected issues with the home I didn't count on (new furnace, all new windows, etc.) but it worked out. 

@Alex Tobias  for multi-family, I would renegotiate the offer if during due diligence something came up massively unexpected by all parties.

This unexpected higher rate erodes a borrower’s expected cash flow and ROI and may change the “out-of-pocket” capital required to close the transaction.The uncertainty affects both borrowers in the midst of a transaction, and those looking to refinance an asset in the next 24 months.

Hi, I have a large unexpected expense on one my rehabs and I'm trying to keep my costs as low as possible on other items. 

I've used Servpro for plumbing accidents and was happy with the service; I'm not sure if they deal with crime scenes.

I also agree with  @Steve DellaPelle in making sure you are financially stable enough and comfortable with the process and any unexpected expenses.

We overestimate our numbers to leave us some room to work with and not fall into unexpected surprises.