The worst ones are the ones with slotted heads where the "backside" of the slots are sloped. 

Even so, assuming an additional $5k in expenses, you would still be creating $10k AND have a cash flowing money making machine. 

One RV slot is being rented out to a guy for $100 dollars a month in a rough looking travel trailer. 

I'm assuming this spike is from the washing machine usage?

That doesn't stop someone from jumping through all the hoops to get a showing and then spring the "oh I just saw you don't allow pets, I have an 8 lb [piss and poop machine] that is very well behaved, do make exceptions?"

The Master account being the one that controls the hallway and basement lights, laundry machines, boiler, etc.

Left messages on their machine.

I have a 12 unit building in a small town filled with great tenants who are older and never entered the 21 st century, They deposit rent checks in a lock box in the laundry room and once a month my wife empties the box and drains a huge pile of quarters out of the coin laundry machines.

Also I am an agent in another state as well so anything I say may be of zero use to anyone and should be treated with similar value as one would take from a fortune cookie, a ZOLTAR machine or a magic 8 ball.That being said, was that your agent or theirs?

If you consider as value-add, anything that lowers the expenses and add to the income (at reasonable costs)You could add storage areaPaid preferred parking (depend on area)Billboard with ads on the property (depends on property)Energy efficiency /Utility efficiency (common areas/responsibility of owner)Coin operated beverage machines