In bitcointalk forum there are really good posts even that does not earn atleast single point of merits.and there are many spam and off topic posts that earn bunch of merits.
And even some forum users does not give merits for quality posts and they share merits with only there friends for some shit posts
Some forum users who tried to make quality posts are now demotivate with this situation
It's too early to decide whether or not the merit system works.
Remember that the thread you post in won't die right after you post in it. You might get a merit a week after you've made the post if it's any good.
I see lots of people complaining about not getting merits from something they posted 20 minutes ago which doesn't make too much sense.