Related topic: System Tray Scan Utility - identify programs that have icons in the tray.
I don't know about you, but I am saddened whenever I use a non-techie friend's computer and see more than two or three active tray icons in the Windows taskbar "system tray"*. (Usually I see six, seven, eight or even a few dozen!)
Why does it bother me? Because, most of the time, the computer owner has no idea what those icons are for, or how they got there.
It means that third-party installers (or worse, computer integrators or 'manufacturers' like Dell) have hooked more stuff into the auto start chain, which also means: more memory used, longer startup times, another prime opportunity to break the user's system with even more bloated, buggy software.