They just expect it to support their lifestyle once they stop working along with some tax deductions. 

I would  show you purchase strategies, real estate monetization, rent roll leveraging, portfolio margining and asset protection/deep tax deductions  

It could help accelerate depreciation deductions, especially with your mix of single-family homes and duplexes.

I assume you deduct it over the next 5, 7.5 and 15 years?

Each year at renewal we ask them what we can do to make their place better, maybe painting a room, installing a new fan,  .. anything up to $200,  so they tell us what they want, and it's fully tax deductible.  

You are eligible to deduct the interest regardless of the type of loan(Bank or seller financed).Best of luck

If you have 80 some rentals already that you bought years ago, I am guessing that the depreciation deductions are running a lot lower now for those units and you're probably paying higher taxes. . .

Make sure the deposits are transferred and not deducted from purchase price, otherwise you will need to come out of pocket when tenants move out.You should also make tenants and landlord sign an estoppel agreement, which outlines important items and agreed to, so the tenant cannot claim to have a huge deposit later or claim that the prior owner gave him ownership of the shed in the backyard.

@Robin Thornton Whatever calculation you decide, make sure to include your insurance deductible on top of whatever you budget for repairs or vacancy loss.

Appreciation is a bit riskier since it depends on factors we can't always control, such as school levies passing, business success, crime reduction, etc.In my opinion, it’s hard as a newbie to jump into appreciation properties, as they require a lot more initial capital to acquire.