The evidence is more than good enough, so red tags and/or red flags can be left on the profiles by you or any member.
Correction: "red flags" (I assume you mean type 2 or 3) should only be created by actual victims of the scammer.
See the Flag creation page:
[type 1] Due to various concrete red flags, I believe that anyone dealing with this user has a high risk of losing money. (This flag will only be shown to guests/newbies.)
[type 2] This user violated a casual or implied agreement with me, resulting in damages.
[type 3] This user violated a written contract with me, resulting in damages.
I meant type 1 flags. Only that I didn't specify the type of flag and ended up looking like I was generalizing.
What do you think if one opened type 1 flags against all accounts wearing the betking signature, which is a known scam? Is it in order, or is it too harsh when it comes to trust flag usage?