Skunky

Ah, that Heineken smell. This is actually a fairly significant flaw. It is caused by the interaction between ultraviolet light and hops. Specifically, when ultraviolet light cleaves an isohumulone molecule. This forms a free radical that combines with a sulfur compound.

Almost all beer in green or clear glass bottles are subject to this, although darker beers seem less affected. Also note that Miller Brewing uses a form of stable hop essences and the beer they bottle in clear bottles is not affected either.