But I think if we have to talk about it continuously without action, the results will not change at all.
The action required is for more users to start regularly reporting spam posts rather than just ignoring them. I don't browse the altcoin boards, but I know there are plenty of non spamming and intelligent users who regularly read and post in Bitcoin Discussion. If every one of these users reported only a couple of posts each day, and we had the mod power to quickly handle these reports, the board would rapidly improve.
I do think we should be more liberal in handing out escalating bans for repeat spammers, though. I get so tired of reporting the same users for spamming day in and day out.
Negative trust with the tag "spammer and will change to neutral if proven to change" I think will help the forum to reduce the number of spam posts on various boards.
Maybe it would, but on the flip side I still see plenty of users with historical red trust for spamming continuing to spam. Regardless of the answer, I don't think it is an appropriate use of red trust, since being a spammer doesn't have any inherent link to your trustworthiness in a trade or the likelihood of you trying to scam. You are free to leave red trust to spammers if you want, but you are unlikely to convince many DT users to do so. I also think temporary bans would do more to push users to change their behavior, and this is the route we should be advocating for rather than leaving red trust.