Some of the Merit source believe in meriting the good content irrespective of post history but some believe in checking it .
But I personally know that post history is checked because couple of time I received merit from same user within a gap of few minutes in two different board. It is very unlikely that user automatically stumbled in my other post that is in another board and not at all trending topic.
In one case I observed that user given me merit in some other post within the gap of few minutes where he quoted/replied to me in some other post.
Both type of cases clearly indicate post history was checked.
I will like to quote my old post to emphasize how post history matters.
7. Put some little more effort in posting.
A little extra effort will pay you in long run and I will explain this mathematically.
.01 is only 1% of 1. If you see at a glance you will not say that .99 and 1.01 is a huge difference.
But a huge difference occurs when they are multiplied repeatedly.
(.99)100 = .3660
(1.01)100 = 2.704
(1)100 =1
1 % laziness repeated in 100 post reduce your chances of getting merit from 1 to .366 but in other hand 1% of extra effort repeated 100 times will increase your chances from 1 to 2.704.
This is important, because Merit giver/ source do look in the history of poster. You might not get Merit for your all posts but if some Merit source/giver decide to give you Merit than he/she might double up seeing your history. In other hand if your continuously making bad post then Merit source/giver can change its mind by seeing other bad posts.