Just an FYI -
In version 6.5 you can upload Graemlins and then just not have them "active" - but they still work if you know the code. I use the WTF one all the time...but my members do not have the code.
Now of course anyone can use a graemlin if they know the path to it...but that is cheating

Post Icons - that is a different story...but a hack could be written to have "levels" set on Post Icons, and Admins see all, where members see most.