You don't see very much spam arriving at the Eternal September or AIOE news servers.
It's pretty much fine as a discussion forum.
Things have been lively in comp.lang.c recently with a little coding exercise going on and such.
comp.unix.programmer and comp.unix.shell are active also.
comp.theory has been quite active due to a crackpot who insists that he has solved the halting problem, or at least refuted common halting proofs using a nested x86 simulator that detects recursion, haha.