You are looking for signs of someone visiting (suitcase) or someone living there (closet is full).Next, assuming occupants not on the lease have moved in you will need to decide if you want to address this face-to-face during your inspection or send an email. 

Although an Airbnb here and there doesn't make much difference, the impact of those 50%+ Airbnb buildings is definitely negative- lockboxes on every railing, suitcases and confused travelers in the lobby, late night parties, cleaners constantly in and out, unauthorized persons entering and exiting the building...You've got a great idea - we own short term rentals in Seattle, Stevens Pass, and Alaska, and our ones in Seattle are EXTREMELY PROFITABLE.

@Blair, any constant flow of strange cars and strange people dragging in suitcases at all hours of the day and night, especially with families, pets, or groups of people will disrupt the tranquility of a neighborhood. 

All guests bring is a suitcase and groceries, they don't need lots of space.

Moving forward, it sounds like you have to suitcase your deals utilizing a pitch deck of sorts this is informing your capital partner that you have the deal ready to go (financing, rehab, timelines, exit strategies, etc) and you are just looking for funding in terms of reserves, cash to close, and capital for the rehab to be reimbursed.

My only goal right now is to not to be afraid to ask questions :). well, that and soak up all this info.As Keller says in The Millionaire RE Investor, a cash buyer does not mean showing up to the closing with a suitcase full of cash.

You took the suitcase all the way to the station on this!

I'm a landlord of a duplex and a couple weeks ago we heard a loud argument (we live on the other side) and then she left with a suitcase and we haven't seen or heard from her.

Can't fit a ladder in a suitcase (although some tools, paint supplies, etc., travel well).