BeerBorg

I had some today. I bought a discounted six of Ruckus Hedonism (not at my usual distributor). After chilling a couple, I poured one before dinner. Before the glass was half full, it foamed over. The taste was acidic, as is some infected homebrew. I also noticed high carb on opening the bottle. A quick search revealed that I'm not the first (though with other brews).
Recently in a bar, the barmaid, knowing I'm a "beer guy", asked me to tell her what was wrong with the Abita Strawberry on tap. First sip I knew it was something, second sip defined it: strong buttered popcorn, diacetyl. She agreed, that was the off-flavor.
So, when you mess up a brew, know that the pros do it too.

Buttery diacetyl flavor can come from dirty taps and lines at the bar, so it likely is not the brewer in that case IMHO. Most dirty lines either present as diacetyl or sour. I like this article on common off-flavor problems that can be caused by the bar or restaurant.

Interesting take, Swen. I usually find that the dirty line/tap has a souring effect. I also find that this particular bar has not had that problem before (though one of the other pubs in town does). I'm not disputing you, obviously I don't know the source. Though I am pretty sure about the bad bottle I opened.

And it may well be the brewer in the bar's case as well, especially if they have a good track record. Or it could have been a missed line by their distributor or whomever they have contracted to do their line cleanings. I think either scenario is plausible. I have definitely gotten the buttery badness at a dive bar or three from the dirty line. as a side note, I can't find an article I read last week (have cleared my history since then), but it was a nice article on the bad things barkeeps do, which includes some cleanliness issues as well as submerging the tap in the beer when they fill the pint. Eww...

When Goose Island started to brew their line of funky beers, I got some infected 6 packs of normal beers. They didn't foam out, but they were sour.

I drank the second tonight, not infected. Some of the reports I read said the same, one or two in a six were bad.
By the way, it's decent beer, not great.

The issue hasn't necessarily been infection, but as I have tried various bottled craft beers, I find some with excessive astringency or flavors otherwise being seriously out of balance, and said "you mean people really sell this stuff?" It does happen to the pros too.

It's true. I've heard from bar owners, beverage managers, and bartenders that sometimes you get a bad batch.