[LearnedfromTV]

Put another way:

He called two raises preflop and check-called the flop. So far, he looks pretty loose-passive. What hands does a loose passive player do this with: an ace, a club draw, a set/two pair (maybe), a lower pair. Which of these is he most likely to bet the river with after the club draw and Q have hit?

AQ, flush are the two the jump out at me. Most people who call three bets in a row need their hand to change to wake up and bet out. Again, not necessarily, but way more often than not.