They say honesty is the best policy.
This short exchange during a job interview illustrates why honesty might not always be the best idea:
Potential employer: Let me ask you this: What's your greatest weakness?Modified from a tweet sent by Jorgen Sundberg>>
You: I'd have to say my greatest weakness is honesty.
Potential employer: That's interesting. You know, I don't think honesty is a weakness.
You: Really? Well, I don't give a rat's ass what you think.