Keeping the current scenario in mind, it should be more than 1 merit to be eligible for bounties. Practically, it the bounty programs that decide minimum eligibility to participate. Some require just a user to post links about their projects everywhere (FB , Twitter or even this forum). Those programs do not care much about the knowledge or contribution of the members on this forum. Till the demand for such users is there, we will not see spam removed from bitcointalk completely.