Having done it for a living for a few months, you cannot possibly imagine how bad it gets.
No, seriously. I already had very little faith in humanity going in, and thought I'd seen the worst the internet had to offer. Scraping the actual bottom of the barrel is difficult to even describe. I had to force a stunned sense of humor about it to detach myself a bit as a coping mechanism.
Correct me if I'm wrong, but I believe by default IRC is only logged if the client opts to log it. I don't remember being able to see message history when joining a channel back in the day, so I'm not sure if servers themselves keep logs by default.