Advertising flights to make money would require the pilot to have a commercial rating and would move the airplane into the commercial category (insurance, 100 hour inspection, etc.) -- my opinion.
Here's another example to consider: I think we've all seen the "What I learned from that", "never again" and articles such as "I flew to Clinton in a 150" , and articles such as "Fun flying the new Legend Cub" or "How I made my first solo flight after only 7 hours of training." Each of these have been written by student pilots and PPL. Yet, once they complete the flight they can write an article and take photos during the trip, and sell the article and photos to a newspaper or magazine. That would not (again, in my opinion) make the flight a commercial one.
