If I am forced to run the dates back to back, and the tenants (former and new) being friends, decided to blur the move out move in dates in that one decides to move things in before the other moves out. 

If you push stuff like this onto a tenant, you are causing yourself far more aggravation and cost in the long run, than just sucking up $200 occasionally.

Occasionally unscrupulous landlords will inflate the rental figures by increasing the rents each year, while simultaneously providing the tenants with a concession equal to the increase in rent, so on paper the figures are higher than the units are actually worth.

We occasionally take out some profits for fun money. 

Occasionally I can find someone who will rent it. 

Sure, occasionally there will be damage, but overall I will come out ahead.

I'm analyzing deals, saving cash and complaining (occasionally).

The only downside is that you occasionally have to raise rents on your friends.

Open up the floor registers and clean them out, this is not only good for your HVAC system, but also will reveal things like cigarette butts (unauthorized smoking), pet food (unauthorized pets), and the occasional kid toy (this is okay, since finding a barbie shoe or the missing lego will make a child happy.) 3.

Although it occasionally happens, you usually do not get a tenant candidate with a great credit score, no debt, incredible income, good neighbor skills (add your list of perfect tenant attributes here) on your first showing.