[PhantomGremlin]

That's interesting. I see

   "dnt": "1"

using Firefox, regardless of whether "tell sites I do not want to be tracked" is unchecked or unchecked.

Could be a bug in Firefox, since visiting your site with Safari doesn't send the header at all (which is how it's supposed to work).

Edit: Sorry about the noise. It's not your site, and it's not Firefox. NoScript took it upon itself to set this header!