My tenants have my cell number and in 18 years have never had a call about a clogged toilet.  

Yes a lot of people spend frivolously…but in this day and age and in our modern society, internet, a computer, and some type of cell phone (really a smart phone) are really becoming absolute necessities.  

For example,  if they receive SNAP (food stamp) benefit or even a free cell phone service,   that counts as income as well, but I believe that non-housing subsidies don't have to be counted 100% toward rent.   

From now on look for devices that secretly record your stay?

Then there is choice as adult, to do what is required, yes it's hard and can suck, to go to college or university, and again PUT IN THE WORK, or not, spend early 20's seeing how many brain cells one can fry.

We are fortunate that they took care of the place and will not need to reference the condition of the unit upon their move-in 2 years ago.Ideally, there would be a checklist that is accessible from a mobile device and could allow for uploaded photos as well.

That's a problem because a.) it misleads people on how safe the outlet is for plugging in 3 prong devices (3 prong devices are better grounded which can save the device in the case of a short but they have to have a third wire in the wall for ground) and b.) by adding extra outlets to an existing 2 prong that has been inappropriately changed to a 3 prong, the outlet can overheat and cause a fire.We'd need to know more, is it knob & tube, is it aluminum, is the panel 60amp, 100amp, 200amp, are there other panels, what condition is the sheathing around the wire to know where to go from here.

Another trick I have to verify employment is calling the main phone number and asking for HR, instead of using the direct line or cell phone they provide.

Don't worry about phones, everyone does cell nowadays....

For promoting it you could use a device like StayFi to send people directly to your landing page when they log into the internet.