What do you mean by a Quality Post ?
Most of the quality posts are ANN threads, services.
In my opinion, there's a difference between quality post and merited posts. If you ask for what quality posys are, I can't give a definite answer since the forum didn't define what quality posts are. But when you talk about merited posts, they are posts that are contributing positively to the discussion at hand.
These posts must not be agreeing to the topic been discussed, it could be a contradicting view but does has meaning and quality to it. While the level of your post quality depends on the users with the smerit that doesn't mean any posts that don't get merited isn't quality.
Some just lack the exposure needed for meriters to see. Providing you're contributing positively to a discussion ongoing and aren't spamming or posting generic contents you're good to go as your post could be considered quality by a merit source and get rewarded.
I actually have to agree with you.
Each of us is different and has a different definition of what quality is.
No rules can be made about which posts deserve merits and which don't, it depends on the understanding of each person.
Some people have more available merits so they don't have to choose which posts to reward with merits and which don't, but some members have very few available merits and therefore have stricter criteria for giving merits.
Also, some parts of the forum are read and followed more and therefore more merits are shared there.
Of course, it is not the same if someone writes in the English part of the forum or only in their local language.
There are a lot of factors that affect the obtaining of merits.
I think the most important thing is to actively contribute to the forum and that will sooner or later be recognized by the community and rewarded.