What does your company do?
Questions like this will make you look unprepared. To avoid that, never ask anything that can easily be answered with a Google search.
How soon can I take a vacation?
Wait until you're offered the job before you start asking these types of questions.
When will I be eligible for a raise?
This may tell the interviewer that money is the only thing you care about.
What happens if I don't get along with my boss or coworkers?
The interviewer may wonder if you've had problems with colleagues in the past — and they may even assume you're difficult to work with.
Will I have an expense account?
There's really no reason to ask this in the interview. Plus, it sends the wrong message.
I heard this rumor about the CEO; is it true?
You should never bring gossip into a job interview. It's highly unprofessional.
Do you monitor emails or internet usage?
This question will raise red flags — something you definitely don't want to do in the interview.
Can I arrive early or leave late, as long as I get my work done?
Don't try to make adjustments to the schedule before you've even been offered the job.
How did I do?
This one puts the interviewer on the spot. If you really want feedback, wait until you get the offer or rejection, and then ask via email what you did well, or could have done better.
Bonus: The worst question of all is the one you never ask.
"Not asking questions can be just as bad, or worse, than asking terrible questions," says Deborah Shane, a career author, speaker, and media consultant. "It can reveal a lot about your communication skills, personality, and confidence — and it can leave the interviewer with a bad impression of you."