I came across this only once. I had to keep biting my tongue not to say anything to offend her, but we got it done and in the end she loved it. The 'gaudy' fabric that didn't fit the color scheme of the quilt was used in the smaller pieces, and imagine our surprise when that fabric made the others around it just pop. Guess it belonged in there after all. As long as she was happy and excited about it, I felt I had to do what she asked, and did enjoy doing it for her.
I don't see a problem with the colors and theme of the fabrics she likes. I think they will all go well together. Think outside of the box and the end result and it may surprise you big time. If that doesn't work, look at the smile on her face when she receives it.