> It takes less effort to uncover a public lie than to uncover a hidden truth.
> Alternatively worded, something about sunlight being the best disinfectant.
That's a slogan, not a truth. For instance: what is "best"? The fastest? The most thorough? Something guaranteed to work, if given enough time?
Even if "best" means it's the "fastest" disinfectant, that doesn't mean it's fast enough to keep up with the infections the op describes.
There's also the question: if you prove something is a lie, will enough people pay attention? A 140 character lie could take pages to debunk. Given enough lies, that page count is going to build up to the point where no one has time for it. And the actual audience of the debunking is unlikely to be a superset of the audience of the lie.