I am unaware of this thing, can you please explain in detail as to how this site asks for payment as this is a free to sign-up forum.
this thread will calrify everything for you https://bitcointalksearch.org/topic/how-does-point-of-evil-work-772564
i know why bitcointalk does that i need to know how can i implement it for my site
i think you need to ask theymos directly or badbear, they are behind the forum
so what i think they've done is they have a list of ip addresses which are blacklisted which have been collected over time and as mostly these are tor ip's it picks it up and the fee is requested
now the question is who gets the btc, i would like my payment in VNL if thats ok
they are collected as donations mostly, they also have flagged some vpn i've tried those vpn on chrome, those extention and they were flagged, but not all of them