Its contrary to BS so if its working for you then consider yourself lucky at this point, but in the future you should resist the urge because it will come back to burn you over time.
If you're a card counter there would be certain index numbers where doubling against 10 or Ace would be the correct play (when the deck is rich in 10's and Aces), but if you're not counting you won't recognize these situations and your better play is simply to follow basic strategy.
tondi: If you're playing a 6 deck game where dealer stands on any 17, your decision to double-down 11 against dealer Ace will cost you 24 bets per 1,000 hands played (long-run), compared to just hitting the hand.
Actually, doubling 11 vs. Ace should be done just by reading the board and it is the correct move to DOUBLE when there are at least 6 or more babies (2-5) than 10's in a multi-deck, S17 game. Then, and only then is it proper to double your 11 vs. Ace even though sometimes you wish you did after getting dealt a FACE!!