Typically there'll be a CMS flag available to powerful users (editors). That's how it works at the Guardian. It sets a boolean (shouldHideAdverts) in our content API[0], which we use in templates[1] to suppress commercial logic. There are obvious business reasons for this. It's common for it not to be in the advertiser or reader's interest to show commercial messages against some content. [0] http://content.guardiana…
It's totally unsurprising that it would be a CMS feature, I'm a little taken aback each time I see a crass juxtaposition on smaller sites (more out of surprise at them not doing it than any particular personal sensitivity to it).