Many interviewers ask potential employees what their worst quality is or why they shouldn't hire them. This can seem like a trick question, but employers genuinely want to know what areas you need to improve in, and the question allows them to gauge your behavior. The question is also designed to get an idea of your attitude and actions in the workplace, so using past experiences will help you show the type of employee you will be.
Think about what your worst quality is ahead of the interview. Don't come up with something that the employer wouldn't consider manageable. For example, don't tell the employer you think violence is a solution to workplace conflict. Instead, name a true quality that isn't unmanageable, such as you don't stand up for yourself enough.
Don't tell the employer that you don't have a bad quality. This gives the employer an impression that you are either lying, don't know yourself well enough or that you are overly confident and can be difficult to work with.
List only one flaw if more aren't requested. Interviewers usually request one of your flaws, so you may turn off potential employers by going off on a tangent.
Let the employer know how you are trying to change or how you would work around your worst quality. Explain how your weakest quality may affect the position you are applying for and what you would do on the job to mitigate damages.
Put a positive spin on your worst quality. For example, if you are a perfectionist, tell the potential employer that sometimes you get carried away with the details of a task.