16) Applications that run on multi-user operating systems but don't understand the difference between users and keep the same preferences for all of them.

I mean, why aren't you just saving preferences in a user-specific location to begin with, whether it be a home directory or a registry or whatever? If I'm logging in as a different user, chances are that I don't want the same preferences. And if I do, I'm probably smart enough (given that I'm one person using two different accounts), to copy the information over or whatever.

Note that none of this removes the possibility of one login user having multiple personalities, as they can still exist in that user's personal config location.

Why can software engineers not figure this out!?!