Maybe good intentions went bad. I thought it was a great idea when the mods/admin gave us the ability to flag posts as spam. It obviously made their lives easier. I know I flag a bunch, but am very careful to make sure that it truly is spam based on the post counts, member date etc.
I did come across spammers hijacking inactive members screen names and brought it to the attention of the powers at be.
When you flag a post, you can flag it as spam or other (violate forum rules) and put comments. I don't believe the comments will show however if someone marks as a scammer.
That being said, I don't look at the classified. I'm not sure if someone is trigger happy and flagging posts that shouldn't be flagged, or as you said they are scammers.