RE investing, whats been the "catch" for you?

[rob in cal]

   On paper the arguments for real estate investing often look really good.  What I'd like to know is in the real world, what kind of issues crop up unexpectedly that screw up the rosy projections?  Obviously things like vacancies, bad tenants, repair issues etc are known about before one gets into the business, but what kinds of things happen way more than expected?

[ketchup]

I've had the same ~2010 era furnace in my rental property since I bought it and it's required a ~$500 fix in both 2013 and 2016. 

Apart from that, just shitty tenants that were my own damn fault.

Oh, and one time a family of two woodchucks and three skunks broke through the floor in the bathroom, but that's just life.

If you buy right, run the numbers conservatively, and screen your tenants properly, you're golden.

[CareCPA]

All of the above.
On paper, my rentals should cash flow great.
In reality, I didn't know the area well enough so I didn't buy in the right part of town. Everything in your original post has happened repeatedly in the last two years.