As a trusted SO user, I barely see any reason to flag.
Spam or offensive questions or answers are handled fast enough by simple votes to close then delete. Maybe because we have now enough trusted users to do it.
The only uses I see are
- asking moderators to revert one of their mistakes like an erroneous closing, but they don't do many mistakes, I had to do this only once
- flagging an offensive comment, but I yet have to find a comment really needing moderator attention
- flagging a spamming user, I did it twice
I see some high rep users manage to get the Marshal badge and, during last moderator election, some candidates were boasting their high number of raised flags.
So I guess I miss something. What ? Why do trusted users flag?