Whenever I finish writing a romance novel, my publisher asks me to describe my main characters (the lovers) in detail. I share my vision of what these two should look like. Unfortunately, the artists and photographers the publisher uses either don't read very well or see completely different people in my novels. Thus, I have the misfortune of telling readers sometimes, "Um, the two people on the cover aren't the ones I put in the novel, so ... sorry about that."
My first cover was very nice, but the rose she held was the wrong color entirely. I let my publisher know. Instead of changing the rose back to red (as it was in the novel), he made me change the color of the rose IN the novel to yellow. Who gives a woman a yellow rose? We weren't in Texas!