The answer is rather complicated I think, in that all non-default view module controls will display in the admin skin defined for the site, which has to do with the way dotnetnuke handles module navigation when you use module definitions for navigation. I tried changing the definition in my own dev portal's event's module from 'view' to 'edit' for grins and giggles, and of course, still got the admin skin. All other modules with 'view' controls will typically exhibit this behavior.

Another type of module uses what has often been referred to as a dispatcher pattern, whereby there is a main module container which drives navigation within the module. These modules (of which the store module is an example) will not use the admin control when 'zooming' in to a detail record.