Believe it or not, it only takes one sentence to turn a great interview into a lost employment opportunity.
After 10 years of running a recruiting firm, I can tell you that interviewers actively seek out the negative traits in the job seekers whom they meet.
Be aware that the following sentences and phrases turn employers off and, thus result in wasted time meeting with the hiring manager. Therefore, it’s imperative to focus on avoiding the following statements, questions and phrases.
“I want to own my own business.” — An entrepreneurial ambition is an aspiration best left unsaid. While it’s a productive goal, hiring managers interpret it as quite the opposite.  They don’t see ambition, but rather a potential threat.
Primarily this is due to the fact that employers fear turnover and stolen proprietary information.
Not only do turnovers carry heavy opportunity cost (managers don’t want to invest time in those whom they feel may be a future flight risk), but they also leave the organization open to insider information being leaked.  The last thing a firm wants or needs is to train a future competitor.
“How am I doing?” — Employers want to hire those who are confident. When you ask for feedback during the interview, not only do you leave yourself open to having to confront negative assumptions, you also come across as insecure which is a byproduct of being ineffective. Moreover, you look weak when asking this question. Interviewers gravitate towards employees who display strength. Whether it be begrudgingly or gladly, we respect people who display strength and self-assurance.
“like” and “um” — These interjectory phrases allude to the inability to concentrate or think on one’s feet.  Especially for higher level positions, these unnecessary verbal connectors are sometimes associated with a lack of intelligence or lack of interest.  Additionally, interviewers can read this as a sign of inefficiency and inability to apply critical thinking skills.
These interjections can also hurt your tone of voice and ability to persuade as most interviewers will respond positively to vocal consistency.  It can bore the audience when you attempt to elaborate on your answers.  Finally, saying “um” and “like” will lead to the interviewer shying away from their main points and losing brevity in their statements.
“What does your company do?” — This is the holy grail of things to never say during an interview. There is no more effective way to turn an interviewer off than to ask this inquiry.  It shows a blatant disregard for their time and alludes to a poor work ethic. Researching specific facts about a company gives the impression that you are thorough in your work, interested in the position and fully invested in getting the job.
“I need to make x amount of dollars.” — The most important lesson in persuasion is that you can’t expect others to care about what you want. If you desire to become more persuasive, get in the habit of addressing the concerns of others before asking about your needs. The most effective interviewees give the hiring manager what they want first, then speak about money later.  As a result, they end up getting more money.
“How long is this interview going to take?” —  People always strive to feel important and the interviewer is no different.  Show that they are not a priority and you’ve just wasted your time as this will inevitably (in the majority of circumstances) turn the individual off to your needs.
In the end
If you’re going to go out of your way to interview, make it worth your while.  Execute by avoiding common pitfalls described above and you’ll be well ahead of the game.