I think merit requirements for signatures are a step in the right direction. It forces users to actually create posts which are valid. This would have to be maintained w/ strict rules regarding merit, and strict rules against merit abuse.
Having been on this forum for more than 5 years, I will admit I have seen a drastic decrease in post quality. Thinking back, bounties weren't really a huge thing, and I think with their increase, and signature campaigns, it was only going to get worse without a further mod presence.
While I think that signature campaigns are affecting this, I don't believe they should be prohibited. But I do believe a "minimum merit" rule should go into effect. IE, signature campaigns can only add members who have a minimum amount of merit per rank (as some campaigns have effectively put into place).
The only other thing I can say is to not let the spam make you avoid that category. Stay in the category, post high quality posts within the category, and report all posts you can.
These are great suggestions I definitely agree with. Minimum merit would make the job a lot harder for alt farmers while forcing the rest of the spammers to probably quit, or get their shit straight(small chance). The only thing I would disagree with is continuing to post in the category, it's pretty pointless to any sane individual. Posting just to get dumpster with spam is not worth the time. People who post quality stuff expect quality discussion in return since they spend a lot of time writing those posts, so when they get broken English non-sense replies I can only imagine the frustration. As cowardly as it seems, I think users should migrate to areas where the shitposting is on a smaller scale and report bad posts there since the results are more likely to be seen.
Along with this, I'd like to suggest a limit for new accounts on how much can they post at the beginning in terms of frequency and the minimum characters per message allowed. I feel it would boost the quality of posts globally across the board. Once you are a certain rank, you are allowed to post more often and fewer characters if you want to(although we see that users of a higher rank usually write longer posts which are higher quality).
I understand where your concern is coming from. I just feel like it's only going to get worse if legitimate members don't hang out there & continue to report posts.
Look at this as an example: https://bitcointalksearch.org/topic/how-many-coins-does-satoshi-hold-5015332
People are only going to start posting threads (which should be in Bitcoin Discussion) in other categories in order to avoid the spam. It's only going to lead to mis-categorization of posts if people avoid that category.
Just my $0.02