Saying "when I'm not an idiot I'm about 1800 strength" is roughly the same as a baseball player saying, "when I'm not striking-out I'm a .650 hitter."
That's not fair, and I think you know it. I have tilted in chess the way I have tilted in poker, and have gotten so frustrated at my play that I'd go off on an idiot-bender and knock my rating down two or three hundred points. I'm sure others have had the same experience. I've also had stretches where I just sit down to play to blow off steam, but I've had others where I take it semi-seriously and have read books, studied games when I was through, ran some stuff through Fritz, etc. When I was taking the game semi-seriously, I was a 1800 player on ICC -- when I was logging in to donk away some time, I was in the 1500-1700 range. (Again, I'm not equating these ratings with USCF ratings.)
The equivalent of "when I'm not striking out I'm a .650 hitter" in poker would be "when I'm hitting the flop I am a fantastic player", and that's not the kind of thing I meant to imply at all.