In the past I have merited a post which I then myself reported for plagiarism an hour later and got the user banned. It's simply not possible to double check every post or post history prior to awarding merit, just as it isn't realistic to expect people to check Loyce's or Vod's sites for every single post to see if a user is banned prior to meriting them. If possible, I would like to always avoid meriting plagiarism, but being banned doesn't automatically negate everything that user has ever posted, and some of their other posts may well be merit worthy.