It’s not really a mission, but rather a courtesy call (self-preservation at times too). Most are pretty logical and natural to comply with, even if you don’t read them to begin with.
Unfortunately, it seems that it’s not something people always do (I took a while), and even if they get merited, either their past catches-up, or they lose sight of some of the basis, as this stat seems to suggest:

https://bitcointalk.org/index.php?action=merit;stats=topsendban

Note: The focus above is on the Receivers on (s)Merits, that at some later point get banned for whatever reason. The Senders are generally faultless in the above context. The more people they try to merit, the likelier to hit someone that is going to ultimately be banned (specially, unfortunately, if the merited profile is of a lower rank).