I'll explain my reasoning. Since I've been running the table over I think it's likely he's raising with middle pair or worse, so I want to let him hang himself. I also think if he has an ace I'm likely behind, so I lose less if that's the case this way. I think it's unlikely he's on a draw, and I'm afraid he'll check behind on the river when the 3rd spade hits, which is why I bet. If he raises I'm obviously in trouble, but I don't think I can fold simply because I'm not sure if folding is correct. It's the old 'I'd rather make a one bet mistake than a one pot mistake.'

I guess the thing that bothers me is that the board is draw heavy, but I'm finding myself less concerned about this the more I play 6max. In full ring I'm always looking for ways to protect my hand, but these days I've been looking to exploit over-aggro opponents more. I'm just having trouble finding the right spots.