Guest postings to me are one of the strengths of mudcat. The guest Marcus (above) who had his question delightfully and promptly answered is a case in point.
I started as a guest, and found the Forum and the Database invaluable: some of the threads from members and guests were of less value, but I ignored them; you don't have to respond. Some of the threads are full of 'in' jokes from subsets of the community. That's OK, I have my own groups too.
Abuse and vituperation are not only found from guests, nor even from UK mudcatters. Too much of a response to this by way of deletion of posts or rejection of guests could lead to throwing the baby out with the bath water leaving a much less vibrant and interesting forum.
My friends know me; I am reluctant to post too many personal details on the web, just as my phone # is ex-directory since my work is involved with offenders and we are advised to be 'discreet'.