One thought on this - how easy would it be for someone to stitch an enemy up to one of these vigilante groups?
Go on there pretending to be someone else and chat up their fake underage girls, whilst at the same time pretend to be a woman and chat up your enemy, arrange to meet up at the same place with both and then BAM. Your enemy is outed as a paedo, gets a kicking and posters all over their neighbourhood.
Yes, I may be an evil genius. None of you should cross me