So the major issues in a house are a foundation issue or a structural issue, the next tier down would be a mechanical issue like Electrical, Plumbing, HVAC, then roof - which isn;t an issue a new roof is very common in a fix n flip, and then the outside facade: Brick repair, driveway repair, brick pointing. 

What happens if the roof has to be replaced?

People were panicking about their roofs collapsing and willing to pay almost anything to get someone up there to shovel them off.

The roof is over the next door properties property line.

Far more than most real estate acitivies and much quicker think about it.. you sell the same info over and over and get paid instantly you have no roofs to fix no tenants to manage etc etc.. you do have reputation management of course.

Like deferred maintenance, (bad roof, worn out water heater/AC Unit, warped flooring, water damage) etc, unpaid utilities,  unpaid taxes, a second loan, unpaid HOA fees, a bad pool, bad reputation, sometimes squatters, sometimes they were drug houses, and so on.

I like good neighborhoods, with sloped tile roofs, stucco siding, built in the last 20 years. 90% of Las Vegas SMF checks none of these boxes. 

Roof is dried in. 

Is there a defined definintion of occupany that mandates a set amount of days per month that I must sleep under the roof of my primary residence?

I’ll also amortize large items like roof over 20 yrs, and then add $100/mo/unit for general repairs.