Sort:  

Well my friend, feel free to flag them. I only have a limited amount of time and voting power you know?

Plus, I don't want to flag anyone with higher rep than me.

perhaps inquiring as to why they've used a tag - and if no response then flag or flag and inquire and remove if you get a chance to do so assuming the untag. Seems like all it would take would be one good lesson - perhaps a pop up message when people log on letting them know they might lose reputation for abusing the system.