One that forever sticks out in my mind was at the Old Fashioned in Madison, where I ordered a Hinterland Bourbon Barrel Imperial IPA. I got the beer, it tasted nothing like it and I asked them if they accidentally poured me the wrong one. They poured me another and it tasted the same. I was pretty persistent, so I asked them to check their kegs and make sure they didn't accidentally have the wrong keg hooked up. After checking it out, the concluded it was indeed the Hinterland beer. I was so mixed up because of this I even went as far as calling Hinterland that night and requested to speak to the brewer. No response. 2 weeks later, I was at a Hinterland tasting and I talked to the brewer about my experience. He admitted that "Imperial IPA" might have been the wrong name to call it since it wasn't really that. I suggested an American Strong Ale and he agreed that they were going to call it that. Really bizarre shit.

I can only remember this happening to me once. It was a year ago at the Green Dragon in Portland. I got 4 sampler size beers and one had me totally confused. I can't remember now what it was supposed to be, but I swore it couldn't be right. I mentioned it to a bartender and he was nice enough to pour me a 1oz taste of the correct beer. It was definitely not the same as the one I got! Color was slightly different and not as foamy. I never did figure out that mystery beer, but at least they gave me a free glass of the right one. The funny thing is both beers were good, but when your head expects certain characteristics according to its style, and what you get does not agree with that, it just turns you off.

i rememeber a couple years back at a bars anniversary party that a fairly rare sour was poured. the colour was off and it was super sweet and only a touch tart, so i ask the company's beer rep (who was there hooking up the kegs and passing out shwag) if it was supposed to be like this. he went in the back and found out that instead of the Bockor Cuvee des Jacobins Rouge, he had hooked up (and drained) a keg of Lindemans Pomme. I was happy though, I got both for free and both were tasty (the Jacobins is an amazing beer by the way, had a couple of snifters just the other day)

can't remember specifics, but I've had it happen where I actually did get the wrong beer, and where the beer was just significantly different...

Can't prove it but there may have been a few budmillercoors drafts I had way back in the day that easily could have been coorsmillerbud instead........seriously how would you know.