How old is the roof?

The landlord just put a new roof on and installed new AC units in both units.

There are some issues with the roof and electrical that also need to be addressed.

Each unit is 2 bed/2.5 bath, approx 1100 sq ft, with separate water meters, small fenced-in front and back patios, new water heaters/HVACs, new plumbing, new electrical, new roof, new appliances, etc. 

Roof Damage can be a deal-breaker, People with a lot of money can be as thrifty as anyone else.

No idea how old the roof is.

For example, do you recommend always bringing in an HVAC specialist, roofing specialist, plumbing specialist, electrical specialist, etc just to make sure that part of the potential rental is working optimally.

Still have to budget for roof, appliances, hot water heater, hvac, bath and kitchen remodel,etc.

So if you eliminate all of those properties that have old roofs, mold, settlement issues, outstanding code violations, and more of the why step in that - I'll call those "bad deals," you can get on with analyzing deals that are worth your time and possibly worth doing.  

The unit is 3 stories tall with a mansard roof, so the work will be up on scaffolds.