Well, the NS-10s definitely aren't accurate. I think it's more about knowing how they sound. The old saying is, "If you can make a mix sound right on NS-10s, it will sound good everywhere." Notice it says, "...sound RIGHT on NS-10s," not "sound good on NS-10s." I've heard that your mixes should sound a little mid-heavy and bass-lite on NS-10s because of the frequency response of the speaker. But man, their translation is supposedly second to none if you know what you're doing.
And from what I've read on Gearslutz, etc., I think Andy started using NS-10s because they could be found in any studio since they were kind of an industry standard. But feel free to elaborate or correct me of course, Andy.
Right now I have ADAM P-11As, and they're great monitors, but I really need some extra $$ for other expenses. I haven't had them long enough to really grow accustomed to them, which is why I'm considering going with NS-10s and using the extra cash towards my mic purchase, etc.