Admin already mentioned, if someone involved with buy sale merit then we should tag them.
That's not
what theymos said:
If a DT member tags you for something stupid involving merit (ie. probably anything less than selling merit), then they're not going to be a DT member for much longer.
Saying they shouldn't be tagged by DT if they're not selling Merit isn't the same as saying they should be tagged when they do sell Merit.