Merit is not only a symbol of quality post. If you notice ppl are getting merits on bounty threads. And few ppl getting many merits on a single post. It appears like merit system is not real.
That is abuse of the system, where two or a group of people agree to merit eachother. If you find such posts please report it at meta section, there are very many topics on this. If you find a lot of these, you can start your own topic and you ll get merited for it.