Codes can be created to identify scenarios of merit abuse that often follow this pattern
Merit abuse doesn't follow a single pattern Codes are not created for their thoughts or subjectivity.
People merit certain group of people not because they are abusing the merit but that's what they find interesting
Imagine a user mostly based in the mining section
Their merit circle Would be small.
Another does the cost worth the perceived results?
Simplicity sometimes is security
If it gets too complex we may start seeing bugs (literally and not literally)
Example: Alice presents a problem, Bob earns several merits by responding with a possible solution. Peter, some time later, presents the same problem and goes directly to Bob's response because it is the most supported one. This is what I mean when I say 'merit-based voting system'. As for the other point, when it is visible who grants the merits, it opens the door to the 'authority bias' effect.
Oh we already have something like this
If you suspect an abuse, just post it on reputation board and case closed.