I've cleaned them with, what you say is, that horrid car wash soap sold in stores. I've gone over them once or twice with Plexus in the almost two years I've owned it just because. I highly doubt anything was done to them by the previous owners, judging by the condition of the paint amongst other things. Wax them with wax when I wax the car itself. On top of that, it's actually the previous years headlights that are notorious for fogging (2000-2002), not the '03+. For having 109,000+ miles on them as well as being 7-8 years old, I think those "crap" products are doing just fine.

An aside: On my 2001 Neon that had fogged headlights when I bought it, I used Meguiar's PlastX. It cleared them right up and I never had another problem that I recall while I still had that car.