Anyway, it has become common knowledge (that no one can find a source for) that legitimate Guinness has too high an alcohol content for it to be allowed in the US. Is there any truth to this?
Could be that they drop the ABV to drop below a tax/excise/levy/theft threshold. I can't imagine it being a legal issue.
Side Note: It is interesting that no one has asked anyone if they "Really drink their beer warm?" I believe that must be one of the main questions that Americans have about those in the UK, at least in my experience.
I haven't been to the UK, but do know a bit about beer. There are various styles that are supposed to be served chilled (~7C, for many of the common ones), but there are also some that should be served closer to cellar temperatures (10, 15C), which may be perceived as warm to people used to beer stored in food fridges (which I would expect to be around 4C). As a very general rule, the darker and heaver the beer, the higher the serving temperature -- for pale larger it's pretty low, but barleywine is on the uppermost end.
As the temperature drops, the hops becomes more dominant while the malts fade to the background. So if you have a beer that's all about the hops with a minimal malt presence, you want to chill it down to help bring it out. On the other hand, if you've got a malt focused brew, you'll find a little more warmth will enhance the taste. 'Course, you can go too far in either direction no matter the drink.
To further complicate things, there's also mulled beer. Doubt it works too well with crud like Budweiser (or VB, or Fosters, etc.), but if you grab something heavy -a porter might be enough, though doppelbock or barleywine would be a better, I think- you may be surprised after heating it up and spicing to taste.