Actually, MOST aluminum beverage containers have a thin plastic lining that is supposed to reduce the metallic taste.
Personally, I never drink out of a can unless/until I can wash/wipe it off, at least with a wet towel/napkin to remove any "foreign deposits" that may be on the can. Consider how they're made, transported and stored. Not the cleanest of environments for something you're about to put in your mouth.
Wash the dammed can off before you use it..NO, you don't HAVE to use soap and hot water, but if you do it right, it won't warm up your beverage. (OK, for you thermodynamics geeks, MAYBE a degree or so, but not enough to really matter)
Sorry, forgot the obligatory links:
http://www.aluminum.org/Template.cfm?Section=Can&NavMenuID=289
" Inside Spraying
A specially selected coating is sprayed on the inside of the cans."
http://en.wikipedia.org/wiki/Beer_can
" Aluminum cans contain an internal coating to protect the aluminum from the contents. If the internal coating fails, the contents will create a hole and the can will leak in a matter of days. There is some difference in taste, especially noticeable in beer, presumably only due to traces of the processing oils used in making the can. Oils used in can manufacturing are FDA approved and must be constantly monitored."
http://www.stevespanglerscience.com/experiment/00000100
"Did you know that soda cans have a thin, plastic liner inside to keep the acid in the soda from reacting with the metal? "
"The History of the Liner - Technicians at the American Can Company, even before prohibition, began toying with the idea of putting beer in a can. As early as 1929, Anheuser-Busch and Pabst experimented with the canning process. Schlitzeven proposed a can design that looked like a small barrel.
The major problem the early researchers were confronted with, however, was not strength, but the can's liner. Several years and most of the early research funds were spent to solve this perplexing problem. Beer has a strong affinity for metal, causing precipitated salts and a foul taste. The brewers called the condition "metal turbidity".
The American Can Company produced the flat or punch top can in 1934. The lining was made from a Union Carbide product called "Vinylite", a plastic product which was trademarked "keglined" on September 25, 1934. "