Topic 5568262
I just saw this and it was really surprising. They pay for posts that aren't even limited per week. This makes every participant feel like they're in a race to make as many posts as possible and earn more money than others. 
I know not all participants registered in the campaign are like that. Now they set a maximum post limit for each participant based on the weekly rating. But the maximum post limit is still quite high, between 50-70 posts per week.
You know many mixer campaigns in the past have max weekly post cap is 50 posts and even the most successful campaign ChipMixer have about 50 participants with that 50-weekly post cap. There is no spam problem with ChipMixer because they only hired most quality, best posters in the forum.

About Stake, they easily hire spammers into their campaign, that's their biggest problem as it's like waste of their marketing budget. If they hire better posters, they would have better effects from same weekly budget.

You can set a 100 posts weekly as a limit but only pay to eligibe posts, and spammers will stop spamming when they realize that spam posts won't be accepted.