I got this question during my first professional job interview, with a twist:
''What would your* former employer* (in this case, my research director) say are three weaknesses that you have as an employee?"
At first, I was stumped. I am an employer’s dream–I honor authority, I am conscientious, I work well with others but also have a high degree of independence… what’s not to love? 
I came up with two.
- I can sometimes be obsessive about little details and check and re-check things to make sure they are accurate.
When my potential employer wondered aloud how this could be a bad thing, I said ‘‘While accuracy is important, sometimes you can arrive at a point where efficiency is compromised.’’
They liked that.
My #2 was: ‘‘My self-confidence. I can be nervous and insecure about my abilities sometimes.’’
(both of these are absolutely sincere and honest answers.)
Then my employer asked, ‘‘What would YOU say is your #1 weakness?’’
And I said, ‘‘My self-confidence. Absolutely.’’
I was hired the next business day.
I don’t worry too much about being open about weaknesses, I guess, because the accomplishments on my resumé speak for themselves. Obviously if my self-confidence was a crippling drawback, I wouldn’t have achieved all those things or otherwise made a good interview.
Now that I have the job, what is my biggest obstacle? Overcoming my own insecurity. They can’t say I didn’t warn them. 
I would not hire someone who gave the response in the OP. Smarmy, superior, overconfident, and evasive. That is a shit answer if you ask me.