Well ... in that situation the only way to realize if you're winning with AA post-flop ... is that you ask? and you do that by making a continuation bet ... what I recommend is never "slow play with AA"
it depends on how preflop action has taken place and what information you have accumulated on your 2 opponents. personally with AA I have 4 or 5 preflop bet to prevent one of my opponents from paying me with too big a ranche. for all-in on the flop or on the turn. but even if AA is the best hand of the pack. I happen to lose with this hand because in the end it's the flop that dictates its law.