[NLTRN] Set on 3-flush board, bet the river?

[chip_nich]

I like a check here.

But it looks maybe more likely a naked Ace or king clubs,with a pair combo.
A flopped flush would more likely reraise turn,and probably would bet river unless you feel villain views you as likely to fire another barrel on the river.
If you bet river,and vilain shoves,you are getting great odds to call but its unlikely he will do this without at least a straight with you having bet all streets.In fact if he did have a 4 he would bet river imo.
It is a close decision i feel,but i would check here.
If he shows a flush you still have 800 chips left.

[Kalledrengen]

I think I check this river, I don't see many hands calling that you've beat.
Ac7, Tx are probably the only hands that could call you that you beat. Perhaps, and only perhaps a smaller set, but that would make him more than a "little passive" as you describe him.
The check on the river could mean one of many things;
His AcX / KcX didn't make the flush, his Jc9 type of hand didn't get the straight/flush. He got a low flush or a straight and afraid of you having the flush.
Something along these lines I think, and the hands you beat will fold to your valuebet and the hands that beat you will call.
Check behind is the best I guess.