Back in the my days in West Texas, Lone Star was the beer of choice in many a redneck bar, with Pabst and Schlitz up there, too. But in other types of bars it was always other brands, especially Coors. This was admittedly a long time ago.
By an elderly Teutonic gentleman, no doubt. 
Would you say it tasted like an old german?
**Hamms. **
Here is how bad it is. Three rugby players (myself included) are traveling home from a game. We had 100 miles to travel, one 6-pack of Hamms that we got somewhere and no stops in-between. We each had a sip, took a quick vote and throw the whole lot out the window. We’ve all had skunky beer before. I can assure you that never stopped any of us from finishing a beer.
In the Houston area, where I lived in the earlier part of this decade, you could buy it in pretty in much any grocery store and gas station, but the only bars that carried it were hipster dives that sold it for a buck a can.
I like the Imperial White, but you’re right that it’s very potent-tasting, and definitely not to everyone’s tastes.
The worst I recall having is Bud Select. It was on sale at a bar by the pitcher, so a friend and I decided to get one to share, being poor college students.
I think it was the only beer I’ve left unfinished. It was just so watery and bland, even more than any light beer I’ve had.
Heineken always tastes skunky to me, but I don’t think I disliked it as much as Bud Select.
Raison D’Etre is 8% abv.
Rheingold is perhaps the worst I’ve ever tasted. Flat and musty, with a rancid aftertaste. Usually found in the hands of a hipster with a faux hawk.
So bad, in so many ways.
Not Raison d’Etre, Raison d’Extra. Clocks in at 18.5% abv.
Tuborg Gold, bottles, Oriskany NY, 1985.
Labatt Wildcat. It tasted like beer-flavoured piss.
EDIT: I forgot about Labatt 50. That didn’t taste good even when I was already drunk.
I am amazed that Heineken is actually on the market. It tastes like it’s made of water, yeast, barley, hops, and dog shit.
Milwaukee’s Best would be my vote.
Personally I like Corona and Rolling Rock, even though both have been mentioned here.
Anything brewed in Canada.
Aggressive is an intersting word choice for it, but I am glad I am not the only one who finds it to be vile. I will freely admit I am not a fan of ales in general, but I can drink them usually. ABA was just awful.
I love Arrogant Bastard!
I don’t particularly like beers like Bud Light, but they’re not bad - just tasteless.
Wost ever is Sam Adams. I can’t finish one. Close second is La Fin du Monde. Blech. Pretty bottle, though.
I actually don’t find Nat Ice or Natty Light that objectionable in the grand scheme of things.
Milwaukee’s Best (or Beast as we call it) is awful, though.
I don’t drink enough beer to have any great warstories, but the worst beer I ever had was some sort of cheap concoction with an American flag on the can. It was so dreadful that, as college freshmen, we mixed it with Mountain Dew, and this somehow improved it. That is, it was so bad that being diluted with that awful swill actually made it better by comparison…
I’m surprised that Huber hasn’t been mentioned yet. We used to buy it in college because it was so cheap (less expensive, on a per-ounce basis, than Coke). It seemed like you could feel the barley going between your teeth as you drank it. And, lordy, the headaches it gave. Just nasty.
Point beer tastes like peanut butter, but a hell of a lot of Wisconsinites like it.
What amused me, when I was in college in Wisconsin, was how crazy Illinoisians would get for Point. Most of us considered Point to be pretty bad, but the Flatlanders found it to be forbidden fruit.
I’m surprised Thailand’s Singha beer has not been mentioned yet. I love it myself, it’s my favorite, but many people rate it their worst. You either love it or hate it, it seems.