This article is from the Eddings FAQ, by Aquarius email@example.com with numerous contributions by others.
There are indeed. These basically revolve around Usenet and general
etiquette; that is to say, constructive criticism is welcomed by authors,
but pointless flames and cries of "what utter cr*p" are not. Remember that
someone put in a fair amount of time and effort to write a piece of fanfic;
if you don't agree with something someone's written, then count to ten, and
*then* post calmly explaining why. If you just don't like a piece of fanfic
and want to post to the group saying just that, don't bother.
Save it for email, or send it to /dev/null.