UTG is a pretty big donk, like 60/30 or something but isn't totally terrible postflop. I'm pretty sure he raises any A preflop so I don't think he has the nut flush here, likely a medium to small spade or even nothing at all. My hand actually might be good, but I don't want to call and lose to like the 5s or maybe he is making a retard bet with Kx (I tend to see that a lot vs donks). Thoughts?

Party Poker No-Limit Hold'em, $ BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

saw flop|saw showdown

SB ($43)
BB ($227.83)
UTG ($338.45)
MP ($290.99)
Hero ($233.80)

Preflop: Hero is Button with A, Q. SB posts a blind of $1.
UTG calls $2, 1 fold, Hero raises to $10.07, 2 folds, UTG calls $8.07.

Flop: ($23.14) 6, K, Q (2 players)
UTG checks, Hero bets $15.52, UTG calls $15.52.

Turn: ($54.18) 4 (2 players)
UTG checks, Hero checks.

River: ($54.18) 3 (2 players)
UTG bets $24, Hero raises to $98.98