Reading
this there is no clear or postulated indicator that credits a post merit worthy.
That thread is clearly an exception. The merit system was just introduced and the readers earnt some merits that they instantly spent. That's my guess. I haven't seen such thing again so intensively.
This could simply be a coincidence or I'm just imagining things.
Can you share us some merit transactions that do what you wrote?
The system only demands quality spots, and quality posts is subjective to the reader.
The system demands meaningful posts, not necessarily high-quality. A funny ad one-line post may be merited, but it can't be considered high-quality.