I reported a domain registered through Cloudflare that is obviously being used to scam people. I first tried the abuse email address given on whois, only to be told that the abuse email address is not for cases of domain abuse. I then tried the Cloudflare abuse web form. I very quickly got a response claiming that there was no evidence of abuse (it's an obviously fake page trying to get people to enter their credit card details). Cloudflare clearly doesn't care if criminals use them to register domains.
