We tried banner towing for a while in the 90s, but the restrictions on overflight and proximity to crowds, plus the noise annoyance factor, let it die a slow death. And big wind days while flopping along at 40kt meant we didn't make it to the end of the desired display area, before having to turn around again.
We also did helicopter RPT between an urban centre and the international airport, the only helo RPT in the country, and the only single-engine. Sadly, the desire for porky passengers to carry massive suitcases, strollers, and even a sewing machine, meant that the weight and bulk space was filled before our wallets. Also, it had taken 5 years to get it approved, and in that time they built a freeway nearby which reduced the travel times to the airport. Lasted for 6 months, another painful death.