I think he'* right for the most part. Most picture threads people post are after they've spent six hours polishing and it'* late in the day. So the sun isn't so bright, or maybe it'* even cloudy. The pictures turn out great that way but don't show any of the swirls or scratches left yet. There are the rare times when people take pictures in full sun with the the sun reflecting off the panels where you get a better shot of the paint.
But you are right, put the car in the garage with a good halogen and you will see all of the swirls and scratches in all their glory.
2003 Black SLE-Stock
2000 Mercury Mountaineer
1968 Oldsmobile Cutlass Convertible-455 cubic inches of muscle