If people are using their advertising budget unethically, you should expect them to find new unethical ways to use their advertising budget once you've eliminated the existing ones. Rather than playing whack-a-mole, take a step back, and see if you can fundamentally change the rules of the game. Why is advertising bad? What do you want to happen? Fixing the "how" too firmly, too soon, is an effective way to produce bad policy, no matter how good your intentions.
What a sad comment.
Ever notice that there used to be a lot of businesses with names like "A+ Heating and Cooling" or "AAA Chimney Sweeps"? That was because being at the top of the phone book's alphabetical listing was more likely to get you business since a lot of people would open to a section, start at the top and start calling.
There's only so much shelf space to go around, eventually decisions will be made about who can put their products on a given shelf.
Any large business with the ability to produce multiple different products will inherently have the advantage of getting more shelf space assuming you want to display all products.
But even assuming you just wanted your shelf space to be a bunch of "per company" catalogs, businesses with more money to spend on glossier catalogs, or brighter inks, or more variations so thicker catalogs will have an advantage.
Then there's names and numbers. Hooked on Phonics gets a leg up on every other competing reading program because they got the phone number that is 1-800-ABC-DEFG, no one else can have that number. The lawyer who gets 1-800-555-5555 (or other similarly easy to remember number) has a leg up on anyone with a random number out of the phone company's inventory.
But I'm curious, what would this perfectly level field you envision look like? How would these sorts of problems be solved?