"What are your weaknesses?"
What do I say?
And that is where preparation comes into it. You can either flounder around and never answer the question and so withdraw your application or you can Google, do tests, talk to people, and look at your past experiences and your personality. And hope to God that you have chosen a flaw and have shown recovery from it in a way that doesn't kill any chances you have. Be honest but not too, choose to shoot off a small toe not the whole fucking foot.
I am currently looking at that for my interview. In one test I identified that I am a terrible saleswoman of myself (probably why I'm not a prostitute, cannot pimp myself to save myself), but my top five strengths include faith, curiosity, innovation, determination, and risk taking. So somehow I need to work out how all of this fits in together and how I can word it all to make sure my foot isn't taken off at the knee.