My day/night job is as an ER nurse, and pretty much the only shoes I've worn for the past 3 years are Crocs. I walk an average of 5 miles a shift at work, and I'm standing when I'm not walking. I've been used to spending $80-150 a pair of shoes for years. Now, with Crocs being $35 a pair, I buy them 3 pair at a time. And, the anti-bacterial bit is very nice for the nasty splashes at work.
It not only takes smart business operations as detailed in that article, but a strong community. Crocs birthed in a community full of power and wealth, and that helped a great deal. Hell, Michael Jordan received a few pairs of Crocs when he came to the club for a golf tournament...
Silver and other heavy metals are bacteriostatic as well. Other substances are bactericidal, which means that they actively kill bacteria.
Antibiotics are bactericidal. You don't want to take antibiotic or bactericidal substances on a regular basis, because you end up putting unnecessary evolutionary selection pressure on your normal bacterial flora. That is, you don't want to kill all the good bacteria, otherwise the bad ones will overpopulate because they have no competition.
I'm guessing that the crocs aren't bactericidal, they are probably baceriostatic.