A POTUS won't quiz a potential Judicial nominee about their position on particular issues likely to come before them and if he did the honest Judge wouldn't answer.
He/she doesn't have to ask anything that specific.
The Judges' backgrounds and decisions are known and thoroughly reviewed by a POTUS' staff before ever being suggested as a nominee.
Obama would never think to nominate a Scalia, for instance.
Now, can a nominee unpleasantly surprise his/her nominating POTUS after they take the Bench? Sure. I can think of a couple off-hand. But far and away a POTUS will get what they expected.
As far as Obama evolving on SSM, you can believe he's been sincere but sincerity has never been one of his strengths.