I get reports that sign twirlers
are very effective in Los Angeles and that the twirlers are so good at
twirling their signs that they get tips from passing motorists.
My book on marketing (Marketing Without Advertising) co-authored with Salli Rasberry, makes a point about the difference between advertising and many other forms of marketing including signage and listing. Advertising is defined as all commercial messages that are intrusive to the large percent of people who aren't interested.
Sign twirlers may be traditionally thought of as advertising but it isn't. Having a dancing human with a sign for your business near your business is a unique form of signage. Call it dancing signage. It is giving information to local potential clients. They can respond or ignore it. It is not intrusive, it is informational in the context of a specific retail shopping territory.
I don't have personal evidence that it works but I sure enjoy watching the sign twirlers do their act.