a) Meriting "too much"?
b) Mutually sending merit among users or groups of users?
c) Sending merit to accounts that seem to be linked by exchange of tokens?
d) Meriting to ANN threads?
e) Which other cases?
Who is going to decide if the abuse is considered as such? That is, is there a "jury" and an "appeals process"?
Please point me to any link or resource if there is any. I do know that merit should be sent to post that are "of quality", but I am asking for something specific.
All the cases you mentioned are suspicious. I am sure they have other ways to track abuse as well which they might not want to disclose.