OK you have a point even though I might take this line sometimes facing a turn bet that looks weak. Also call flop/raise turn is a much stronger line so hopefully our increased fold equity compensates somewhat for the worse odds (maybe wishful thinking).

This being said, even if I don't have flushes in my range and A8 is the top of my range, why in the world should I call a shove from a range that crushes me? Now you can say "if you're never calling then you are exploitable". Well I may be, and villain may know it and consider calling the turn raise with any crappy hand comforted by the fact that he will be able to bluff me out whenever a spade hits. Point is, his spade outs, bluffing or real, will only hit 16% of the time. So yeah he will win the hand 16% of the time (a little more considering he could hit better two pairs or trips) but in the long run I still win because he called a turn bet that vastly denies him the odds to win the hand 16 or 20% of the time, doesn't matter if he bluffs or bets for value OTR.

Now yes, if it gets to the point that I am loosing too much value because I am getting bluffed too much, it will be time to adjust and make hero calls to teach'em bastards that I am not negotiating, even if it costs me chips now to loose less later.

But for now, all I am interested in is whether a call on a spade river facing a shove is +EV, and the answer is no.