I think when you check/raise flop then check the turn it kind of turns your hand face up as a flush draw that has given up. If you have a value raising hand like two pair, bottom set etc. you would continue on most turn cards especially as it didn't complete the flush so I think you should be doing the same with your semi-bluffs.

That gives your opponent a chance to fold on the turn (though I don't think he will very often) and will make your bluff on the river more credible.

Especially with the overbet on the river it seems like you're saying "I've missed and I want to win the pot". Maybe a more 'value-y' looking bet on the river might have got the job done and if I was checking back the turn I would probably bet closer to $2.50-$3 rather than $4.

Plus if you do continue on the turn and he raises you could probably throw your hand away and if he calls you, you can check is stats (if you have any on him) and decide whether or not he would fold if you shoved the river.

This Overbet OTR in villain's eyes means flushes or air. Don't know if u'd bet that large with straight or less and if you are betting thin, u r probably folding to a raise.
So, what kind of spade flushes would u x/r flop? 85s, 67s? There are much more missed draws than value hands on your perceived range, I think.

just raise and bet bet shove. this seems like great hand to 3 barrell with as bottom of range no sdv and spades got there

Why did you decide to XR the flop?
Why didn't you continue betting the turn when called?

We could discuss the flop line but there's quite a lot to consider there and it's not coming to mind at the moment. So I'd rather hear your reasoning first.

However, what does strike me is the importance of continuing to bet the turn. When you take this line the opponent will typically peel the GS hands on the flop, and then be forced to fold them on the turn. (JT, J9, T9, maybe 97, 96). You pick up additional outs but you still don't have any showdown value. I'd rather bet and put the pressure on his draws rather than check (representing a give-up or strange double trap kind of hand). Checking makes it harder to win the hand.

When the opponent checks back the turn he could still have a fair amount of draws in his range, as well as some Qx. The J river does connect with him pretty well as it pairs JT, J9 and gives T9 a straight. Given your strange line I don't expect Qx or Jx to fold the river. 8x might fold because he has third pair, but I wouldn't be surprised to see A8 calling either. He still has some missed draws that beat you, such as higher FDs and straight draws - losing the pot against these would suck a lot.

I think we have two options on the river:
- Give up.
- Bet a size that targets non-pair hands that still beat us (better FDs, 97, 96, 76).

Consider the following:
- Betting $4 into $3.5 has to work 4 / (4 + 3.5) = ~53% for it to be breakeven.
- Betting $1.44 into $3.5 has to work 1.44 / (1.44 + 3.5) = ~29% for it to be breakeven.

You need to consider which portion of villain's range you're targeting with your bet size. If you want him to fold Qx, I think no bet size would work. (Maybe AI). If you want him to fold Jx, I would reason similarly. He's obviously never folding a straight or flush versus any size. 8x might fold to a larger bet but always call $1.44. However, Ac7c might fold versus the small bet. Kc7c will very likely fold. 97, 96 and 87 will fold all day. (And they would also fold versus an even smaller bet, like $0.88 - but there's a slight risk of inducing the spazz). Anyhow, that's some food for thought.

Bet bet shove.