Define "absolutely NOT accurate". Barring server misconfiguration, disk/filesystem failure, or deliberate tampering with the logs, I don't see any way that the web server logs can be any less than absolute in their accuracy regarding which pages were served, at what time, and to which IP addresses.
Referrers and user agents are the only things I can think of off the top of my head which go into my logs and are susceptible to spoofing by users1 and those shouldn't significantly affect the accuracy of log-based analysis.
Absolutely agreed that it's all in the interpretation, though.
1 OK, technically users could spoof their IP address as well, but that's a relatively sophisticated technique and they're not going to be able to see the returned page if they do it, so I'm comfortable with ignoring them for these purposes.