You have two options here to make your quest topic. The first one is Bounties (Altcoins), where there is a high chance to see insubstantial posts from bounty hunters. The second one is Service Discussion (Altcoins). The chance is quite low to see useless posts in that section. Service Discussion (Altcoins) is the most suitable place for the quest discussion between those two. The best thing would be to create a self-moderated thread and delete insubstantial posts for avoiding all kind of uncertain inconvenience. In that case, you (the quest topic creator) have to observe the replies of the topic on a regular basis.