Corona and RR definitely don't qualify as worst.
They are far above everything else on the list.
Although some may not be fans of dark beer, that doesn't make them bad.
Milwaukee's best is the worst I have tried. But I pretty much can't stand any mass-produced standard american beers like Bud, Miller, Coors, etc. They all taste bland and nasty. If I'm going to drink a beer, I want it to have some taste. So I usually go for microbrews if available. If I'm just drinking to get drunk, I'd much rather buy a bottle of cheap rum and drink rum and coke all night. Much better than crappy beers.
The only standard american beer I actually like is Michelob. It's pretty good.