I wonder how many of those opining on the "Schedule E vs Schedule C" question have ever booked an Airbnb.  After early opposition to the concept, in the last ten years I have accumulated a couple dozen stays, at least, at Airbnb listings -- about half of them domestic, half overseas.  Several immediate family members have as much or more experience.  

Before the Internet, a short-term rental involved placing a classified ad, or a sign out front.  Today, to run a successful Airbnb, you need expertise in marketing; customer relations (with prospective, current and former guests, from all over the world 24/7); and hiring such contractors as photographers, housekeepers and maintenance staff. 

One thing that increasingly is not required, is real estate ownership.  Many Airbnb vendors are leasing property long-term and then renting them short-term.  

So please, look at the facts and circumstances of each taxpayer.  If the question is, "What can I get away with?", then either Schedule C or Schedule E will probably work.  But if it's, "Doesn't this really look like a business?", then be open-minded and honest.