It's easy to forget how hardcore this game was. For example...
I'm playing a necro (worship bertox). I needed some bone chips for hunting in karanas, found a nice camp of skels in SK. Cleared it prob. 10 times. Never notice a faction hit.
Decide I need to visit a necro trainer - no problem, run to qeynos. Enter temple of bertox in aquaducts, con the front guards - indiff. Great, not kos, head on in! (The entire Temple of Bertox guild kills you). Run back, see that the front guards on are different faction, everything behind them is 'threatening'. Nice bait and switch.
Do some research, find out this temple is mostly Bloodsabers faction, which I trashed when killing those skeletons (I thought it was like a bandit faction or something). More research: find two easy kills I can camp to fix Bloodsabers faction - stay there til Bloodsabers dubious.
Now not kos, so check out the temple of bertox, making sure to con everything before approaching because I had identified at least 3 different factions down there already. Enter the last room, 3 dudes aggro blind from around a corner. Turns out they are on Opal Dark briar faction, which had also gotten trashed by killing skeletons. My camp also had +opal dark briar, but only from 1 of the 2 spawns, so it improved half as quickly, making me still kos.
Conclusion: a human bertox necro could, just by getting bone chips for his pets in karanas, become kos to every necro guild on Antonica at least. With the wealth of information out there now I was able to fix this, but I can't imagine how frustrating it would be when the game was new....