Nothing new in terms of the warning side. To quote from Dick Gaughan who is very much an old timer on the Internet (even if he doesn't seem to use Mudcat much)

"Do not say anything to anyone on a newsgroup that you would be afraid to say directly to their face if they were a 6'6 240lbs ex-professional heavyweight boxer carrying a baseball bat and accompanied by three unmuzzled Rottweilers and a posse of very short-tempered bikers. You never know, they might be - and they might live just round the corner from you. Get the idea? So be as courteous and polite as the circumstances call for."