Use some Mothers mag/aluminum polish w/ the red label. It works as a compound/polish on the lenses and I will guarantee if you add some elbow grease in two coats it will shine ruby red as a mofo. Try it on one lens and then you decide.
I don't have any problems with my rear taillights, but my front taillights... those give me all kinds of problems... J/K
Sand them with some very fine paper, then polish them back up. Repaint the bezels if you're really feeling ambitious, and they'll look as good as new, if not better.