20 years ago I worked on CeBIT for Philips. Next to us was Plextor who just released their iconic 8x2x2 cd-writer. After the whole week I asked the engineers why their billboard had the CD laying up-side-down in the tray with the purple/green up. (I don't remember which colour it was).

They said they haven't noticed and the only person saying something was me. I think I still have a picture somewhere..