Not just of contractors, but gas receipts, food receipts, etc.We are currently using Cozy.co to do background/credit checks, collect rent and record expenses.

Here's what AirBNB/VRBO provide to me, a host, that those sites don't, that I find particularly valuable:- Easy interface that I didn't have to build myself- Credit card processing- Customer service representation, guarantees, and "insurance" that, while definitely less than perfect, provides an element of support and a sense of safety to both guests and hosts- Most importantly, a monstrous marketing presence and household name recognitionThese are costs that far outstrip simply running a website that acts as a way for guests and hosts to connect.  

As a home owner, for safety of my tenant I am keep fixing but violators are keep knocking out.

I’m mainly concerned about safety and liability for the tenant.

Safety - Learn about Crime Prevention Through Environmental Design (CPTED) and employ the concepts at your property.

Scope out neighborhoods within your target price range and research rents, schools, safety, etc. anything that is relevant to you3.

Usually free food and free drinks.

I would -- in this case safety should be fairly cost-effective. 

They are concerned about their safety and don't really know what to expect when they enter so they prepare for the worst as I am sure you can imagine.

It's a part time commitment. 3-5 hours a day, but it's also every weekday, so it is more consistent than a fast food type job.