Mark Thorson wrote:
> Shanghai McCoy wrote:
>> We're not talking IPA here... I believe the OP referred to a citrus /
>> sour taste in a cloudy glass of of Coors and a Keystone... both from a
>> can...
>
> It wasn't sour at all. It did have a citrus-like note.

Another possibility was that it came from a brewery that does multiple
beer types and they accidentally canned the wrong kind in a batch. It's
rare, but it happens.

Someone accidentally loads a batch of "Bob Six Pack" cans on the
automated machinery when the vat they're processing has "FuFu Brand"
instead.

Hops and yeast can both contribute a citrus note to beer, as can some of
the bacteria that can spoil beer. Some beers are purposely "spoiled" by
introducing selected types of bacteria (various types of Brettanomyces
being common).

You might have gotten a batch that was only a little bit spoiled, or
spoiled by the right type of bacteria.