Villain is 46/22/1.75

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver Cards)

UTG ($49.50)
MP ($29.05)
CO ($49.75)
Hero ($74.40)
SB ($53.65)
BB ($46.35)

Preflop: Hero is Button with , .
1 fold, MP calls $0.50, 1 fold, Hero raises to $2.5, SB calls $2.25, 1 fold, MP folds.

Flop: ($6) , , (2 players)
SB checks, Hero bets $3.5, SB calls $3.50.

Turn: ($13) (2 players)
SB checks, Hero checks.

River: ($13) (2 players)
SB bets $12

Is this ever not the flush?

Passively played weak ace sometimes.... only sometimes though.

I often check the flop here. If he calls with a flush draw you're usually going to give a free card anyway, so why not give the free card now and charge him on the turn? You can also induce a bluff that way or you give yourself a chance to catch up if he has the ace.

On the river I've stopped paying these off so much, but I think weak aces are part of his range. Probably pretty close either way.

Yes. Because of the turn check Villian can bet a lot of hands there.

Looks like a naked baby flush draw that villain was ready to abandon, then got checked on the turn and hit. Don't check the turn next time. Still do call this, getting 2:1 with two purr.

Right, but I think this is too big to a blocking bet with A-rag. Personally, this where table image comes into play... not as much yours as your read on the villain's. If he appears to be at all nitty, I believe we can muck here with relative ease.

For the average unknown, the range I would assign would be :

FlushA, Aces up (AQ could fit the action) , sets (AIR is highly improbable based on his OOP call both preflop & on the flop)

there's no value in a turn bet.

Are we value betting a blank river?

You don't think a flush draw is calling a turn bet?

I think you can rule out sets purely on the basis that he has not attempted to get any value from his hand until the river.

Line seems to fit AQ, KQ or a flush (and possibly JT). His VPIP is very high so his range here is definitely broad enough to include many suited connectors and maybe some gappers too.

Some people are saying weak aces, I think that is wishful thinking unless opponent is very loose post-flop, but then so is JT. As someone stated it is too large to be a blocking bet and is a weak ace really betting pot on the river for value? I don't think so.

I cannot really put his range on anything we beat despite the fact we are getting nearly 2:1 on a river call.

Oops, Edit: -nearly.