Improvement books - black and orange.

[Perec]

On my desk I have two books, one is a book on improving fitness, the other is about improving business. Different authors and publishers. Both books are white, both use capital letters for the title, both titles are split between orange and black fonts. Exactly the same shade of orange.

So, is this random coincidence or is capital letters in black and orange on white a colour scheme known to draw buyers to "improvement" type texts?