I do bluff once in a while with very good reason - probably more than just once in a while too. And then sometimes I do exactly what bjsaust described here - see a flop, think they miss - take their calls to mean they don't trust me and continue for no good reason other than the pot is big and the only way I can win it is by bluffing - completely ignoring whether it's a good spot to be bluffing in and whether I have any fold equity at all.

I do also have hands where I'll bluff two streets and be too afraid to fire the third barrel, only to see the hand they showdown and KNOW that they would have folded to the third barrel if I hadn't been a chicken. That's not so much something I'm working on - it's more important to me to control my spewy plays when I've decided I have to win THIS HAND for no good reason.