While there is an extensive (yet old) specification for the core language, the CLisp folks just didn't consider that standardizing a 'standard library' would be a good idea, and as a result each and every implementation features it's very own implementation of threads, networking, GUI,
[BTW: CLISP is just an implementation of Common Lisp, please don't confuse it with the language itself] Yes, this is a problem, but it isn't as bad as it may seem. Do we have standard threads/networking/GUI in C? C++? (POSIX doesn't count - a lot of C/C++ code is written for Win32) What about 'standard' threads/GUI in Perl? Yet these languages are quite widespread.
And the worst, I think, is that the Lisp community doesn't seem to see how some kind of standard library (as in, including the batteries in Clisp) would be useful to bring people new to the language in, or keep them there.
Not true. Look here.
Then again, actually reading comp.lang.lisp (or -- god forbid -- asking a question there) is sadly more than enough to drive you very far from trying to code in lisp ever again.
cll does indeed attract some number of strange trolls. Also, Lisp newbies in initial stages of their enlightenment do post some strange stuff sometimes. (When one begins to 'get it', things may seem much more cool than they are in reality for some time. It's important to learn the language a bit instead of inventing 'perpetuum mobiles' after learning a few nice features). But overall I was never insulted by anyone there though I did post some thoughts. And I don't think anyone will get flamed by cll old-timers unless he/she posts something implying that everyone else on the newsgroup is an idiot.