Orchids are not my thing, Blencowe, but I did do a bit of research in my houseplant/greenhouse book - they do not mention clear pots under the instructions for repotting, and they don't show clear pots in the pictures either, so I'm not sure how important it is, though it did say to use specialist orchid compost. Certainly they're sold in clear pots quite often, and I know they quite like to be pot bound, and that the roots often hang out over the top of the pot, which is fine (and one of the things I hate about them) but will eventually need repotting. Perhaps you should post a separate question asking for info on this.