There are few topics as polarizing and annoyingly superficial as which beer is "piss-water" and which beer is "good beer."
I currently live in Cologne [1] (~1.000.000 people, west Germany) ~40km away from Dusseldorf [2] (~600.000 people, but capital of the state). These cities are the prime examples for rivalry between cities all over Germany. Both are cities that heavily rely on tourism, both are very much into carnival (one of the topics that are discussed to death) and both are _the_ place to be for (different types of..) beer.
Here you get 0.2l (i.e. tiny) glasses of rather light beer, brewed in a way that is even (as far as I know a first!) a protected regional trademark akin to Champagne. You can create it somewhere else, but you cannot use the name (a derivation of the name of the city, Koelsch [3, contains a reference to the rivalry as well]).
Dusseldorf is famous for (larger glasses, 0,3l or 0,5l) stronger (in taste), sweeter and dark beers. Not protected by law, but they are more or less _the_ city for these types of beer.
This leads to a lot of (mostly friendly) discussions like the one you used. In fact, since the local beer here is very light and served in these tiny glasses, ~most~ of Germany compares the 14 different brands of beer here to a kind of 'diluted water'.
It always amuses me (moved here, so I'm kind of an outsider) to see these kinds of discussions and I think like to be reminded (thank you!) that this is a global phenomenon..
1: http://maps.google.de/maps?f=q&source=s_q&hl=de&...
2: http://maps.google.de/maps?f=q&source=s_q&hl=de&...
3: https://secure.wikimedia.org/wikipedia/en/wiki/K%C3%B6lsch_%...
http://t3.gstatic.com/images?q=tbn:ANd9GcTfcLU1Vom4t8DEKwMDv...
How undrinkable is Fosters? We had a '70s theme party once (Foster's is iconic of the 70s here) and I bought a six-pack of Fosters for the humour value (and copped some abuse, too). In the morning, every drop of alcohol in the house had been consumed, even left-overs in the back of cupboards. It was a hell of a party, with empty cans and bottle everywhere, and the punch bowl would have been bone dry were in not for fruit remnants. The six-pack of Fosters remained untouched, pristine in it's carrier in the dregs of the ice tub...
Every pub in a town center will have one of those 3 beers on tap, unless it's very trendy and has no taps. Every off license stocks it too.
Over all, Australia has better beer, but there are some pockets in the U.S. where there is some kickass brewing culture. I lived in Wisconsin for a bit and they do have a better drop than we do in the East Coast. I mean, Leinenkugel & Stevens Point both brew stuff that's widely available and very much enjoyable, up to bar with Boag's here in Australia.
When I went to London a couple of years back, I found that the beer was actually quite enjoyable, though I can't remember which beers I had while I was there. (More as a result of time rather than of the beer)
Madison sucks, move along, nothing to see here..