This is one that I've seen come up quite a bit at my level ($.15/$.30) - somebody just check/calls all the way down the board, even with top pair and a pretty ragged board.

Party Poker 0.15/0.30 Hold'em (10 handed)

Preflop: Hero is CO with , .
2 folds, UTG+2 calls, MP1 calls, 2 folds, Hero raises, 1 fold, SB calls, BB calls, UTG+2 calls, MP1 calls.

Flop: (10 SB) , , (5 players)
SB checks, BB checks, UTG+2 checks, MP1 checks, Hero checks.

Turn: (5 BB) (5 players)
SB checks, BB checks, UTG+2 checks, MP1 checks, Hero bets, SB calls, BB calls, UTG+2 calls, MP1 folds.

River: (9 BB) (4 players)
SB checks, BB checks, UTG+2 checks, Hero bets, SB calls, BB folds, UTG+2 calls.

Final Pot: 12 BB

Results in white below:
SB has 9s Tc (one pair, nines).
UTG+2 has Jh Ks (one pair, kings).
Hero has Qc Qh (one pair, queens).
Outcome: UTG+2 wins 12 BB.


He gives absolutely no indication that he has the King, so am I wrong to keep leading out in this situation?

A flop bet wouldn't be bad. There's no reason to think anyone has a king yet. Since you didn't bet the flop, the turn bet was okay. But don't bet the river against three others with a K or A on the flop since people at that level LOVE playing AXs and KXs.