IIRC there were three campaign participants on the list of spammers since couple of months ago and it was Yobit / Secondstrade / Bitmixer and since two of those are improving, the next one is surely Bitmixer campaign now (one step at the time). I used to monitor their owners activity and he seem to be online only in a limited manner and only entertains few PM's base on my observation alone and sure enough I think a similar approach should be taken towards him until he cleans his campaigns participants list since there are a lot who are getting paid for little to no effort.
On a side note: There are a lot of users that need to be kicked out of their campaign for violating their own rules but again their owner is too late to take actions.
Well bitmixer should get their own campaign manager or a modertor like what yobit did when they assigned hilarious to managed the spammers if that's the case.
I just don't get why bitmixer is allowing this people to tarnish their reputation because of what their participants are doing. If he's not making any actions then maybe it's only fair that he gets a red tag just like what happens in secondstrade. He only took action when he noticed the red tag.