I haven't tried Relax by Davidoff (it isn't available here!) but Kouros does get ugly on me after a really nice opening and decent middle. Maybe it's supposed to do that! I don't know, it's too late now I sold my bottle!

Zino by Davidoff doesn't get so ugly though. I was mostly referring to the cool water series which I really like, especially Deep, but that I got fed up with because of how they broke down over time.