50nl FR QQ vs. check-raise on under flop

pokerstars GAME #16174382855: HOLD'EM NO LIMIT ($0.25/$0.50) - 2008/03/22 - 19:13:04 (ET)
Table 'Zimmerwald III' 9-max Seat #6 is the button
Seat 2: Seamus Jack ($24.60 in chips)
Seat 3: LIONHEARTFF8 ($50 in chips)
Seat 4: cpickell ($49.85 in chips)
Seat 5: zachvac ($59.55 in chips)
Seat 6: Chezowan ($49.25 in chips)
Seat 8: porcupine69 ($106.20 in chips)
Seat 9: RBRTT ($11.15 in chips)
porcupine69: posts small blind $0.25
RBRTT: posts big blind $0.50
*** HOLE CARDS ***
Dealt to zachvac [Qd Qc]
Seamus Jack: folds
LIONHEARTFF8: folds
cpickell: raises $1 to $1.50
zachvac: raises $2.50 to $4
Chezowan: folds
porcupine69: calls $3.75
RBRTT: folds
cpickell: calls $2.50
*** FLOP *** [8d 7s 5s]
porcupine69: checks
cpickell: checks
zachvac: bets $6
porcupine69: raises $9 to $15
zachvac: ???

villain is 25/15/5.8 over ~100 hands

Folds. What hands check raise here? The range of hands that would do that mostly has QQ crushed, AA, KK sets, 87soooted. Granted you might be able to fit 99-JJ in there, but it's such a small % of the possible holdings it's not worth going broke.

Do you have any reads? I have a feeling this guy was bluffing.

But most of the hands beating me here don't make sense to do this either. With that kind of board is a set really going to check-raise? 2 pair? What happens when a 6 and/or spade hits? All of a sudden not only does he have cause to worry but he's not getting value out of me if I do have a hand like QQ. That's the thing, I don't even know what hands do this at all. Even a straight could be afraid of the flush draw. 46s or 69s maybe?

And no reads other than the stats there, I'm multitabling.

i dont mind shipping it in on this flop, people generally c/r with combo draws (pair + OESD, TP + gutshot, etc) and occasionally show up with something like A8 often enough to make stacking off here profitable.