Seriously what you should be asking is to stop all bounty activities on this forum if you only have pure intentions.
So if the current staff of bitcointalk wants to have more quality it should actually ban all promotional activities
This is very true. If we want to see an instant drop of 100% of the spam on Bitcointalk all we need to do is remove every pay per post offer. We would also see a significant drop in spam across the forum from all campaigns if the pay rates dropped. Don't be fooled by people saying a lower pay rate encourages spam because it's actually a higher pay rate that gives incentive for spammers to come here and squeeze in as many posts as possible.
When I reverted the pay rate in the Stake campaign the number of posts for the week instantly dropped a large amount after barely anyone left which is undeniable evidence that lower pay rates cause less posts in total and that means less chance of spam.
Think of it like this, are you more likely to spam Bitcointalk and force posts out if you make $100 per post or 1 cent per post?