I'm confident I can tell you which is which out of the following beers:
Miller Lite
Miller High Life
Bud Light
Budweiser
Rolling Rock
Any Wheat Beer (could tell you that its not one of the others, probably couldn't distinguish brands)
Any Pale Ale (again same as Wheat)
The American macrobrews I listed above all have a distinct taste and I'm sure I could do it. Telling the difference between a Rolling Rock and a Heineken I may not be able to do because both taste skunked and I don't like either. But I've drank more of those macrobrews in the 6 years I drank than most people would do in 20 years.
Its like that Mythbusters episode with Vodka, the expert was able to distinguish between cheap and good vodka and even got the correct order on the number of times the cheap stuff had gone through a carbon filter. If you know your beers well enough you can do it.
The catch in your little study Raybay might be that if you are serving them at a bar. First off, lots of people go to bars having already drank some, this allows them to still get drunk but save a lot of money because you guys charge $4 a pint, that doesn't make for good distinguishing abilities. Second people are used to drinking their beers out of bottles or cans, when you switch to keg beer it tastes slightly different. If you don't believe me buy a can, a 20oz, and a 12oz bottle of Mt. Dew and note the differences, all the same beverage, all taste different.