Joe's right, in that some of the flamers display a high level of intelligence and knowledge about music, but they also have a sociopathic element - a sort of cyber-tourette's syndrome, which means that they just can't help pissing on other people's chips.
For which the only solution is to ignore them, not rise to the troll and wait for the "episode" to pass.
In the case of Guest £1 - the prompt for this threat, maybe - h/she is quite capable of lucid, intelligent comment, and I enjoy some of his/her posts. The snide crap I just write off as an "episode" and ignore accordingly.
It's still a pain in the arse, though!