Well if this user (whom got accepted) is not spamming and shitposting, i don't know who is:
https://bitcointalk.org/index.php?action=profile;u=1178512;sa=showPostsArchive:
https://archive.fo/RHmkSSome responsible manager (like yahoo or aTriz) would never accept such a poster into their campaign, and probably add them to their blacklist. This user is just an example of a poster who has made 0 contribution to the forum, and gets encouraged to spam even more because of getting paid for it.
See my second point, i.e if a person is making "spam" posts and not getting paid for it(seeing as he wasn't accepted in the last sig camp he applied to) , its not counted as (sig)"spam". And well if he keeps posting in bounty, according to the rules he just won't be paid.
As for mentioning merit, its a system meant to keep spammy users from ranking up and is only adopted by some sig campaigns the same way Trust points are adopted.