Some things that may need upgrading are sink faucets (and perhaps the sinks), electrical sometimes needs some help.

If something needs to be looked at, I do a quick one-over look while I'm there - mostly checking HVAC filter, floors, and under sinks for leaks.

I'd tell them that the problem with a disposal is that they often result in plumbing problems, where people think they can dispose of things down the sink that they can't.  

There was no water conservation in place (shower heads, sinks or toilets)3.

So no kitchen sink or lower cabinets either. 

I received a text this morning that my tenant had left the water running in the kitchen sink, and it overflowed to the condo below.  

Also when I inspected their unit prior to placing an offer a few holes were in the walls and the new bathroom sink had a corner broken off of it.  

Quick check under sinks to see if there are leaks, check the a/c unit to be sure it's not leaking inside (window units), listen to see if the toilet was running, check smoke detector batteries, ask if there were any maintenance issues, and off to the next one.I gave them several days notice, so they could plan for it and to have time to clean.It really doesn't matter how messy it is in-between inspections.  

If the garbage disposer is backing up into the dishwasher, then the dishwasher line isn't routed per installation instructions as it's supposed to have a high point above the drain pipe level of the sink.

Check for water damage under all sinks.