As others have pointed out, Listerine effectively combats gingivitis, but gingivitis never seemed to be much of a problem until Pfizer needed a better way to market a new product. And with that we have the unfortunately eternal problem in understanding policy proposals, theories, concerns and solutions by anyone who might have an interest in the outcome (no matter how tangential or hidden). The question will always remain: is this just the next gingivitis?
To take this blog's most recent example we can use the estate tax. The goal of the Republican party and anyone Republican or not advocating repeal of the estate tax is simple: convince as many Americans as you can that they should be worried about a gum disease called gingivitis. Once you convince them that they should be worried, show them that you have the solution. It's easy actually, just gargle twice a day for 30 seconds and stand up for what is morally right--and the gum disease will go away. Informing people that only the ultra-rich are at risk of gingivitis is not a compelling argument. That information should be avoided.
The average American needs to feel that he is at risk. We're talking the farmer, the small business owner, the upwardly mobile professional, the middle class family who still hasn't given up on the "American dream," the old who will see it faster and the young who will see it eventually. Inform people of the advantages to a healthy mouth. We want people to have healthy mouths. Then they can be productive members of society and be able to enjoy the lives they've worked so heard to earn. If you don't use Listerine the entire American economy will suffer (and that's not to mention the whole moral issue).
So am I saying gingivitis doesn't exist? No, but what if I told you that only the wealthiest 2% of Americans will even be at risk of gingivitis? Then you'd know that Listerine is still a pretty good mouthwash, but saying that gingivitis targets small business owners, farmers, or even rich Americans may not even be dignified by a response from the American Dental Association.