But on the other hand, diversity in market investment isn't a horrible idea either, right?

I will say that when I started out I was a "machine gun" investor and I hit on a horrible deal that took me several years to get out of at a substantial loss.Sit back and watch a little while, make every shot count.

Well stated Jay.On BP we have too many investors ranting about how horrible their PM is.

Gutted: he took out the carpet and padding and the walls need to be painted and the smell is horrible.

There have been a few posts lately about buying super cheap properties and why they can be a horrible deal.  

Infact being overly insured, and a provider covering you for an actual incident is a horrible outcome.

I keep researching companies and each one I find seems to have horrible reviews.

This is horrible to hear, but unfortunately, insurance doesn't cover that kind of thing. 

The wife was a horrible tenant.

Would also add to your list of "Cons" horrible city/state planning with highways constructed along river (destroying valuable riverfront) and aging viaduct through heart of Hartford (separating 10,000 Aetna employees from downtown) which I believe has been one of the biggest detractors from the state.