I cringe anytime I get lured into opening variations which my opponent no doubt has thought through 15 moves in advance. As Black I set upon the Scandinavian Defense (1. e4 d5) and decided to study it as my defense to e4. As White I hate facing the French Defense so much I just usually play d4 or f4.
I've topped out around 1600, but I suppose that is the price for not learning the labyrinths that the Sicilian, French, King's Indian, and Queen's Gambit are.
As white I dislike playing against the dutch because I haven't studied it at all and consequently have no idea what to do.
Against 1. Nf3 or 1. c4, I usually play 1. ...f5. White almost always transposes into the Dutch with d4 at some point, and then we are on my ground. Against the Petroff I like to play 3. d4 and either sacrifice a pawn for rapid development or regain the pawn later with advantage. This avoids the drawish, symmetrical, queen-exchanging lines of the Petroff.
As white, I usually open with 1.e4, and am quite happy to face the Sicilian, French, Caro-Kann, Alekhine and other non-symmetrical openings. After 1.e4 e5 2. Nf3, Ruy Lopez or Philidor is fine, too. BUT when the opponent answers 2...Nf6, the prospect of facing the Petrov makes me uneasy. I just don't know how to handle this opening, and my enthusiasm for the game drops.
As black, I know how to handle 1.e4 or 1.d4. BUT when the opponent opens with 1.Nf3 or 1.c4, there is a whole bag of transpositional possibilities that makes me edgy. I don't know whether it will turn out to be the Reti, English, or are we going to end up transposing into QGD or some reversed Sicilian...