So much misinformation in only a few short posts.
First off, the KWS isn't "ONLY" for clean ships, and it's not "best" to use it in anarchy systems. KWS tells you if the ships are wanted by factions other than the one controlling the current system. 80-90% of the time, scanning a wanted ship gives you greater bounties than just the local one. All you're doing when hunting in an anarchy system is removing any chance of getting a local bounty AND making it more difficult to see which ones have bounties (there is a surefire way which I will get to in a second). Any perceived state of gaining "more and better" bounties in anarchy systems are likely just misconceptions of a few pilots. I've made millions off hunting ships, and hunting in anarchy doesn't give me anything better than what I'd get in a 'hisec' system. It's just a trade off to me: I need to manually check if a ship is a pirate, but I also can shoot whoever I want and I don't need to worry about the fuzz spoiling my party.
Now, as far as hunting wanted ships in anarchy: if you're just haphazardly shooting at anything that moves, you're doing it wrong and wasting time. Even though you need a KWS to make any money in such systems, you don't need one to figure out whether something WILL have a bounty. Perform a standard scan, which takes two seconds, and check the subsystem tab in the nav panel. If the ship is equipped with a cargo scanner and/or limpet launcher and an FSD interdictor, it's a pirate, and it will have a bounty. If it's equipped with a KWS scanner and an interdictor, it's a bounty hunter and will likely be clean. Cargo ships don't really have any identifying equipment though...it's not really possible to tell the smugglers from the haulers just from reading their gear setup. You would think smugglers would employ heat sinks, at least, but that doesn't seem to be the case.
Anyway, the slice of truth to the "more money" in anarchy thing is that ships with bounties on them are much more frequent there. This makes little difference to me, though, because the frequency of ships with huge, juicy bounties (I practically never go for anything below 20k and even that's wasting my time a bit) doesn't really change between systems for me. If you're a novice hunter in an eagle, an anarchy system would be a nice place to save yourself some time.