Mute is a good option and solution sometimes, but in my opinion, it wouldn't do the thing when it comes to more serious spammers, scammers and constant abuse of the platform (this way or another).
By muting we would only avoid seeing the content and/or comments by the author we are annoyed with, and that's all. In other words, the account owner would continue to farm the reward pool without any consequences as there would always be hundred of others who wouldn't think twice even less check before they would give their vote to such member/account.
When there is a Flag, things, however, start to change a bit.
Therefore, I think only waiting for somebody else to do the "police work" for and instead of us (just to stay on the safe side), it's not the best solution either.
As @sherlockholmes already said, @steemcleaners is overburdened, and the flagging is, in fact, a downvoting option given to us for a good reason. The only thing we should take care of is not to abuse it. In other words, use it for a good reason and with caution.
Caution being the keyword, and I also think that we should confront the Steeminan and try to talk some sense into him/her, letting them no that if they don't stop that it will result in a flag. If this doesn't help then a flag is a viable option. But always check the Steem Power of the person you are flagging.