So on the leather cases it says in the description that overtime you will get a circular mark on the leather case, and the last image in the gallery shows what it'll look like. Not sure what to do really. I'd prefer the clear case, but I worry about it yellowing, and dust getting trapped in the back and looking awful after a while. Has anyone used any of the previous clear cases and can comment on how well the seals around the edges of the phone are at keeping dust out, and whether they yellowed over time?