You want to know rental prices for each unit. The last assessed tax rate. How the utilities are paid, ie, each unit has its own billing or if its all comon. What the building rates for utilities are that are not covered by the renters. Age of all building utility like water boiler / heat or anything like that and if they are on a maintenance contract. And as you walk around you are inspecting for what repairs need to be done. No need to look impressed by what you see, you are only looking to see if the property will be a cash generation machine or money pit.

Aka ack like a landlord