Joey - I have had this EXACT same problem in my studio for a few years, and I have never been able to work it out. The only workaround that I've come up with is to record DI tracks in another room (on another floor in my house) and then reamp the tracks in my studio. There is some type of "interference" (for lack of a better word) that only happens when I record in my studio (which is actually a small bedrrom on the second floor of my house), and it only affects instruments with pickups (guitar and bass) - it doesn't appear when I reamp tracks that were recorded elsewhere, or with keyboards, synths, drum machines, etc. In my case it definitely wasn't cabling, it wasn't an electrical issue, it wasn't dimmer switches, it wasn't anything that anyone thought it could have been.
I've tried EVERYTHING including shutting down the main breaker to my house and running only a laptop (on battery), apogee one interface and my guitar. In my studio - buzzing noise like crazy. In my living room - no noise at all. And I can also do the thing that you mentioned where if I move my guitar around, there is one TINY little spot in my studio where the noise goes away (almost completely) but it's such a small spot that trying to record an entire take in that position, hunched over in this really wierd spot is 100% impossible.
It sounds ridiculous but the only thing I can think of is that my niehgbors have some type of device that is causing it (baby monitor, wireless 'something,' or maybe it's even my wireless water meter?), because my studio is about 10 feet away from their house (gotta love the suburbs of NY...). I've actually given up trying to figure it out, ever since I found my 'living room workaround,' but I'll keep an eye on this thread to see if you have better luck than I did.
Good luck.
Bobby