I for one have found rye and/or rice hulls to contribute a greenish-gray color to my pale rye beers (I have used up to 40% rye malt several times). Since rye and rice hulls so often go hand in hand, I'm not entirely certain if the color impact is due to one or the other or both. But just take a look at rye malt sometime -- it's downright ugly! And then those rice hulls... who knows where those have been!? What I do know for sure, in my experience, is that I think it's possible, especially in the case of a Rye APA or IPA, for the brewer to have used a high rye content to enhance flavor and head, and with that, likely some rice hulls to go with that rye for fear of stuck runoffs, etc. I have since learned that I need to rinse my rice hulls, but I haven't brewed a rye beer or used rice hulls lately to note any color impacts in rinsing versus not, positive or negative. Eventually I'll know with greater certainty whether it's the rye or the rice that's made my rye beers so dang ugly. But, they're tasty!
For whatever it's worth (approximately nothing), I have also succeeded in making a green cider once. I researched this and discovered it was due to a high copper content in either the apples themselves or in the processing equipment for the juicing. In any case, over time the green stuff eventually dropped out and left behind a normal yellow cider, and it tasted just fine. One of the best ciders I have ever made, in fact.