Idiot, Greedy, or Unlucky?

Ultimate Bet No-Limit Hold'em, $.25 BB (8 handed)

UTG ($139.75)
UTG+1 ($24)
Hero ($29.15)
MP2 ($17.35)
CO ($4.05)
Button ($8.80)
SB ($12.55)
BB ($11.35)

Preflop: Hero is MP1 with 9c, 9h.
UTG+1 calls $0.25, Hero calls $0.25, MP2 calls $0.25, CO folds, Button calls $0.25, SB folds, BB checks.

Flop: ($1.35) 9d, Ks, 3h (6 players)
BB bets $1.6, UTG calls $1.60, UTG+1 folds, Hero calls $1.60, MP2 folds, Button folds.

Turn: ($6.15) Qd (3 players)
BB bets $0.25, UTG calls $0.25, Hero raises to $3, BB calls $2.75, UTG raises to $18.4, Hero raises to $21.15, BB folds, UTG calls $0.

River: ($48.70) Jd (2 players)

Final Pot: $48.70

Results below:
UTG has Qc Qh (three of a kind, queens).
Hero has 9c 9h (three of a kind, nines).
Outcome: UTG wins $48.70.

I made a set on the flop, but just smooth-called to encourage betting on the turn, since it looked like a raggedy flop to me. I didn't think there was a straight scare card that could come ... but I was totally wrong. Not only was the Q a straight scare card, but it also completed my opponent's larger set.

So I believe I should have either bet the pot or just gone all-in on the flop.

Does anyone think the way I played it is correct?

Do you always go all-in or bet the pot in a situation like this?

(Any comments would be appreciated. Thank you.)

UTG is not letting go of those queens.

U were scrizzewd...

I would not go all in on the flop with this id slowplay for max value, prbly check/raise all in on the turn. I can't count the number of times the flop is lik A74, i have a set of 4s and i check raise the guy who has like AJ all in. Or the guy who didnt raise with AK pre flop...

Try betting the pot especially with a face card on board, people will think you have TP, you'll still get paid off, um.. most of the time

I like the slow play, but...

Even a 10 beat you on the river, I might have laid it down there thinking that some guy with 10 K just runner runnered his straight.

*punches UTG* Raise preflop with QQ dumbass!

You almost busted his ass for not raising preflop which would have been great, get em next time.

So I guess I bet the pot then... or check raise the flop and turn.

Isn't Zangief that commi from Street Fighter?

With no flush draw on the board, I have no problem slow-playing trips. The call on the turn was ok. You have to know what kind of player this guy is. QQ I never would have guessed, I think my thought process would have been deciding whether he had KQ or JT, and in the end I'm sure I would have called. That is a huge bet though, and my first instinct reading through the hand was JT. I would have to know that this guy was the type of guy who would call that bet on the flop with an inside straight draw to make that fold though. Like I said, QQ isn't in my radar without a raise pre-flop.