Have you ever said to one of your employees "You have a bad attitude"? If you have, I seriously doubt you knew what the hell you were talking about. I see advice all the time about how to handle the employee with the "bad attitude," and almost all of it is garbage.
Think back to the last time you shared this fantastic news with one of your employees. What probably happened was the employee did something unexpected, unappreciated, or otherwise unacceptable to you. That rubbed you the wrong way. What people usually mean when they say "you have a bad attitude" is "I don't LIKE you!" After you told the employee "you have a bad attitude," what probably followed next was something like "and YOU better fix it." And whether you said it or not, what you clearly meant next was "or else!"
Congratulations, you just dumped on your employee. Did you feel better? I hope so, because you accomplished NOTHING with that employee, and you taught every other employee that observed your display of decisive leadership that you are at least inept and probably an asshole. Whatever your employee felt, I guarantee you that your diatribe left them with absolutely no clue how to change their behavior to improve.
Stay away from attitudes! Focus instead on the bad behavior you observed in your employee. Explain clearly how the behavior did not meet expectations and then engage the employee in dialogue to find out why they behaved that way and what it would take from both of you to change that behavior.
If you insist on talking about attitudes, I strongly suggest limiting yourself to learning how to look for the specific attitudes job satisfaction and organizational commitment in your employees because there is a LOT of research that shows those two attitudes do significantly affect employee performance. Once you focus on a specific attitude, you can take specific actions to try to change that attitude with the expectation of changing the specific behavior you think was associated with the attitude.
You need to stop talking about "bad attitudes" and for that matter "good attitudes". Both of those terms managerially useless because they are void of specificity and real understanding.