Peter, we've been selling rainbow roses and here's our experience from a retailer's perspective.
(1) Rainbow roses are polarizing, love-or-hate items. What I mean is that some people absolutely love them, while some people hate them. They think the dyed roses are too "unnatural." There's not much we can do about it, because that's their preference.
Now because *some* people don't like them, we don't/can't use rainbow roses in any regular arrangement. It would be too risky to do that (also it's visually odd to mix rainbow roses with other "natural" flowers). So we sell rainbow roses only when a customer specifically asks for them. This certainly limits the sales potential and any campaign, Oprah or whatever, surely will increase the sales of rainbow roses.
(2) Most rainbow rose buyers buy only a small quantity, like one stem, three stems. I don't think it's necessarily because of the price. We charge $8/stem, so we are talking about $8, $24 purchase here (in comparison, we charge $55 for one-dz regular roses arranged in a vase).
I think they are buying rainbow roses because of curosity, or WOW factor if you will. Now here's what's important... *If* they are buying rainbow roses for curiosity reasons, once they've seen it, they may or may not buy again especially for that kind of money ($8/stem).
So in summary, these are what we've obseved so far. Some people love rainbow roses and other people dislike them. Most people, however, are curious about them (therefore buy a few stems to see "what's in it.")
If my analysis is correct, Oprah campaign will definitely increase the sales of rainbow roses tremendously. But after a while, people wil get used it (especially if ProFlowers/FTD start selling them) and eventually lose the curiosity factor. You would have made a ton of money in the process though.