I'd say the AirCal-livery, even with the American titles, in the thread starter doesn't even come close to being in the top-100 of ugly liveries - the ones in reply 2 beat it by far, and I'd personally add the current liveries of KLM, Alitalia, Aer Lingus, American, United, AirTran, Vietnam Airlines, Air Zimbabwe, Air Mauritius, Air Seychelles, Air India, Gulf Air, Malaysia Airlines, Air Pacific, Alaska Airlines and most not-mentioned other Chinese carriers into the lineup before AirCal is even thought of...
Of course, there are those - fortunately replaced - liveries of US Air, Continental (the "Meatball"), Delta (especially the one they had throughout the 80s),
BA's Landor livery, SAA's Flying Springbok (though I have fond memories of flights on planes with that livery), AirLanka, Varig, Aerolineas Argentinas...
Not to mention, of course, airlines like Lufthansa or Air France that don't even have a livery - they just fly around plain white planes...
Regards,
Frank