Bonnie/Rob:
My least favorite iris is a NOID iris that shows up from a vendor, when you were expecting something else very fabulous to be in it's place. And I can add to that, the iris that moves from "disliked" to "hated" is that NOID you have waited 3 or 4 years to bloom, only to find out it is not what you ordered and it is ugly to boot. Luckily most vendors only make the occasional mistake and I think an occasional NOID is understandable. I know I am not very good at it. I just sent Debbie from SC an iris and forgot to even label it.
As far as the most unappealing Iris I ever saw? It was this tannish/yellow dull as can be dull dull colored NOID received from a vendor, that I just dug up and through it the trash. It is the only Iris I have dug up that I didn't offer to others first before throwing. I feel a bit guilty saying this but I was thinking, this world will be a little bit better with out this particular iris growing in it. I don't know, maybe like ugly dog contests, we should start having an ugly Iris contest. If we do that, I think I through away the grand prize.