I would say that my most disappointing plastic purchase was one of the early ions, a blue, medium, no stamp, textured bottom from when they first ran their medium plastic. I wanted to like it. I really wanted to like it. But I just never gelled with that particular disc.. And so it sits, collecting dust on my shelf. I haven't gotten rid of it because every once and a while I think, "Hey, lets give the ol' Ion another shot at the bag." But meh.