Absolutely!!! I've had people show up at the field that had spent lots of sim time "teaching themselves to fly". The time it took to teach them to fly was almost doubled because I had to "un-teach" the bad habits and practices they had picked up on the sim. A sim is a fantastic training tool if you use it to practice what you have learned from your instructor. But as Chuck said, it's not much value if you are practicing bad habits.

Ken