Nope, not dragging through print books looking at covers because not enough interest in cover colors to pull me away from my book just now.
I'd no doubt feel differently if tweeting, pinning, tumblr, insta-/booksta- gram, etc. posting where a photo says so much and the hashtag is so important. Not so much just here on my booklikes posts. And not at the point in the story arc I'm currently reading.
I'll be curious to see what everyone else comes up with as their ROYGBIV.
Challenge details from http://boutofbooks.blogspot.com: "Book Spine Rainbow. Take a selection of your favorite book spines to make a rainbow! Share on Twitter or Instagram with the hashtag #bookspinerainbow and #boutofbooks, ..."