My qualm is that it would be impossible to enforce. And I don't really think that false marketing is as big of a problem as most people think because marketing tends to sell simulations, not promises of reality. When you see most advertisements, they're promising simulacrum: a hatchback filled with happy-looking, outdoorsy people; axe body spray being insatiable to women; someone actually drinking diet Pepsi (editorializing a bit on this last one). You don't need to make marketing claims if you just imitate the idealized form. This seems to echo many American politician's rhetoric: the entire Democratic field is representing an idealized form wherein their presidency could somehow overcome the blockade of the Senate.