If anything Cain seemed confused why there was any question about his position which he'd repeated multiple times already.
Cain is also correct, and Santorum admitted as much when he defended prior negotiations and operations, when Cain said we should not second guess Netanyahu's decision. We don't have all the facts available to the Israeli PM.
He did avoid the 14th amendment, a "gotcha" question meant to drive a wedge between Hispanics and the GOP. In a head-to-desk moment, Bachmann took the bait and said "anchor babies."
Fortunately, Cain and Perry did not take the bait, particularly when the question was boiled down for Perry to whether we should repeal the 14th. The press is spinning it generally against the field, "candidates take the 5th," but Perry gave the only sensible answer: NO on repeal.