FWIW, Cardassian women seem to prefer red lipstick...
..But blue-green makeup on their foreheads and neck scales.
Now, obviously makeup may be chosen on a purely artistic whim, but oftentimes it's based on exaggerated biological colors, typically those indicative of arousal or youth. So we might start speculating that Cardassians do
blush, yet they blush blue-green. It may not be a capillary reaction at all, yet it is probably the functional equivalent to blushing in the ethological sense: it indicates arousal or excitement or exhaustion.
It may be a gender-specific thing, too. But the way the forehead "spoon" on Natima Lang was accentuated might suggest that the "spoon" is a special location where blushing is often prominent, even if not quite as prominent as the makeup. So in this theory, excited males as well as females may demonstrate mild greening there, but the shadows mask this from the camera. Only in the idealized imagery of Cardassian beauty queens and kings, athletes or porn stars would the area flare bright blue-green.