Do you think that a ban will solve the situation with these accounts? I think it is not difficult to guess that if someone is so stubborn, they will find a way to return to the forum with a new name but with old habits. Therefore, in this case, and all similar situations, there is no point in a ban. All accounts have negative tags, which are great at scaring everyone away from having any connection with them. A new account bought or created, but in the same hands, is much more dangerous than an old and well-known scammer.
I partially disagree with you. I've seen scammer (who have high rank and have some negative tags) add scam website on his signature and write non-spam post on board that doesn't show trust number. If those scammer are banned and forced to make new account, at least they can't use big-sized signature or attach image without additional effort (such as obtaining merit or spending money on copper member).
sincerely speaking one thing a hate in this life is been scammed by someone, and it pain me a lot when ever I see other people who got scammed by scammers. so in this case I have to agree with what @ABCbits said for scammers to get banned from the forum. Normally if Those scammers are banned from the forum they will definitely return back to the forum with another name, but their old habits of scamming people will still be there no doubt, but they should get banned first, because if those scammers are banned from the forum for them to come back they have to creat new accounts and they will still have to put in efforts by creating good threads and making quality replies for them to obtain merit to grew there accounts which will take them some time to grew there accounts before they can start their scamming activities, especially if they are not good contributors in the forum. and secondly there are also some scammers with high ranks and negative tags and with scam website on their signature that can make posts on a board where users trust aren't display, and if a user who is just new to the forum is not careful enough he or she will go dealing with that scammer account, because of the high rank and end up been scammed, But if scammers are banned from the forum, especially those with high ranks reverse is the case, because a newbie account hardly scam people this time around, because no user will like to have anybdeal with a newbie account.