You want to visually inspect for leaking or rust. 

I'm concerned about a potential leak but would definitely get annual maintenance.   

Many of these are indicative of a sloppy and rushed build, including: -closet shelving crashing to ground 2x-garage door bracket falling off-septic tank bubbling up through ground and not capped right-window leaks-ac fan going out-dishwasher motor going outI've asked my property manager who says it definitely is above average the number of problems I've had.

Also it rains every single day here, so wanting to prevent mold risk and leaks. 

Pex for instance, if not installed correctly can leak at the connection joints.   

My fire was started on an inside wall from a fireplace being over-used and a leak in the metal chimney.

@Bharath, I am far from a pro but I am mentoring with friends who are pros in the RE game who warned me about houses with leaking oil tanks.

They aren't going to care who answers the phone as long as somebody fixes their leaking pipe.

I have heard from other investors in Minneapolis that for duplex it can run $80-$120 can be more depending on leaks and # of people in the buildinng.

If there are no permits on the bathroom remodel, how can the buyer know the pipes aren't leaking behind the walls?