If negative feedback is only used to tag someone when they have already scammed, then it is useless.
It not useless. The tag then save others not to fall in the same trap. Loan default accusations are the best example.
Two user is question in the topic. starmyc and nemgun.
I quote from starmyc
He took the stuff, and even asked me for a refund for a previous work.
There were two jobs. The first one was paid and supplied. He must be talking about the 2nd one. JollyGood took the 2nd work but since he was not happy, he even asked for refund for the first work. starmyc obviously is conducting a business in the forum (from the stuffs in his signature). You and me know JollyGood leaves feedback for no serious reasons but it is not necessary for his potential clients to know who is what in the forum. They will see the feedback from JollyGood, starmyc lose his potential clients.
Read (including the quoted message of JollyGood) where I am coming from for nemgun:
https://bitcointalk.org/index.php?topic=5195361.msg52985918#msg52985918I don't think it's justified to keep him tagged. JollyGood even decided to block his PM LOL