My 1600 rating here is only because I am beating up on lower rated players. I am about 1400 on other websites.
Same here, as an aside, and for the same reason. My peak USCF rating was 1848, but I normally hover in the 1700's, but my site rating is currently 1920 because I am getting wins from lower-rated players (although Niculae from Romania, a 1450 something player, is net points positive against me- he's got my number!). I'm playing for fun and will play anyone.
I should also add that every Nunn book I've ever read has been great for helping all aspects of my chess. He writes stuff that "sticks in my head", and tends to surface when I am playing tournament games. My successes come from him.