An alternate explanation is : the sand camo paint pigment gets quickly deteriorated by UV and turns into a pink shade, expecially under hot and sunny climate. During WW2 already, this phenomenon could be observed, mostly in North Africa or Pacific theaters, where P-39 and P-40's Sand Brown camo scheme parts were quick to turn themselves into 'Desert Pink'. Unlike reco Spitfires however, this was more a happy accident than a deliberate choice. And yet, pilots realized it was still effective as camo. So it became a kind of signature.
