Did you report the others? 1 in >50 doesn't sound that dramatic.
Yes, I did. From CB records it appears that I reported nainaike, sitenetlife, xiaofeifei171, businessmenugui, menubook and 24hourloanz (in addition to today's provider of escorts). Are they in your 50?
Cleaning them up after the fact requires manual action and is by definition reactive. If the spammers are considered a problem then surely a pre-emptive solution is preferable? Obviously if it's going to be a bind to code then that's a consideration too.