Whats to old for an IPA. I mean given a date on a bottle how old is to old for purchase. 4 month, 3months, ect..?
The brewer should have something to say about their specific beer, but I would say most tend to fall off noticeably within a few months (around 3 or 4). It also depends on whether they've been refrigerated or not.
It totally depends on the beer. I consider Apocalypse Cow and Double Trouble to last better than most.