Almost everyone can tell when they’re being advertised to. And almost everyone can tell when they advertise. Effectiveness of such bans would depend on enforcement, the definition is clear enough.
It really isn't though. There's so many different forms that we can't reduce it to "I know it when I see it" territory and depend on case-by-case enforcement.
Do we ban outdoor billboards? Product placement? Content marketing? Public relations? Sponsor logos on sports uniforms? Brand logos on retail clothing? Mailing lists?
I do love the idea, but doubt its feasibility. Implementation would have to be meticulous, and I expect the advertising industry would always be one step ahead in an endless race of interpretation. We can still try to curtail the most disruptive forms though, we don't have to destroy all advertising at once to make a positive difference.
Content marketing, public relations, mailing lists - no
"we don't have to destroy all advertising at once to make a positive difference"