I’ve learned to hedge myself against advertisements. As soon as I become aware of someone trying to sell me some product or service, I pull out.
There are big differences among musical genres, bands, venues, and artists.
Yet they all make use of posters, flyers, a website and advertising in order to appeal to their audience. Like commercial companies, they are attempting to communicate in the most professional and polished manner possible and are going along with the pulp of information trying to reach an audience.