The altcoin bounty managers just don't give a shit whether they're employing spammers or not, and in fact I suspect that's exactly what they want. Unless the forum starts holding them accountable and makes them tighten up their standards, there's nothing any of us can do about the problem. Still, I'd be interested to hear what others have to say about this, because the problem that you've mentioned is pervasive, serious, and really needs to be addressed.
Tl;dr: The managers are the problem.
I sorta disagree with your stance that the Manager are the whole problem. You have to look at the whole point of the bounty campaign to understand my thinking here I think.
Companies do these bounties for many reasons. My belief in their main reason being is they get these coins created and want to do marketing at 0 cost to them. They have to put 0 out of pocket money into the campaigns from that point. They could care less if users are spamming the forum, or if accounts are being banned for posting trash. All they care about is they get some exposure for bottom dollar. Hence why you see all these new managers popping up. These reasons are why I feel its the companies fault and not the manager.
Instead of being eager to accept a campaign, these newbies taking their shot at managing bounties should be more firm in options they offer.
So, I suppose technically it is the managers fault for accepting the job, but not all managers are shit. If you look at the bounty campaigns I have done you will only see 1 bounty campaign that I ran that had a signature campaign along with it. I will not accept most bounty campaigns that want a signature campaign ran with them usually. I believe if Signature campaigns were disallowed from bounties, the whole forum would benefit and see less of the bullshit spamming. Signature campaigns should only be a paid advertisement option IMO. Either the company can afford it or they cannot. No ifs, ands, or buts.
Bounties should be reserved for all other forms of marketing. Twitter, facebook, youtube, blogs, etc. This would only cause clutter in each particular bounty thread and not all over the forum being as users have no reason to spam everywhere with all the bounties being off forum activity. The only thing that might contradict my opinions here are the translation thread. I personally believe having a billion threads translated and placed in each local board is retarded, but I have allowed companies to utilize the option. I would be just fine if it was banned from bountires too and companies were forced to put a little more effort into their webpage and have it in many languages instead.
Anyways, these are my thoughts on bounty campaigns. Maybe Theymos will read and agree with some points