Heh, "gorm" is pronounced gurrum. Surely if they're gormless they *haven't* got the blues!

Rua is used for red in natural things: hair is red, a fox is red, autumn leaves are red. I suppose, too, it suggests a *russet* red.

Dearg is used for red-dyed things, and also for the red of roses, and the red of cheeks. Pink is bándearg - white-red.

Same with glas and uaine - glas is for natural greens, uaine for dyed greens.