The four to flush semi bluff

[Verdi]

I don't have any specific hand histories available but I would still like to discuss this concept. I've taken a lot of heat in the post hand discussions after using this play on two occasions lately.

The first hand I had two low spades in late position in a non-raised or min-raised pot. Flop has two spades. There are two guys betting relatively much maybe 10% of the buy-in. I decide to go all in to win the pot right there and then. I get one caller. Turn is a spade. River is also a spade. The caller had AA with the ace of spades so he took it down. I'm not sure I would call with AA here... Or is that too weak?

I hadn't been on the table for long and no one had a read on me. Was it right of him to call with AA? It's still just a pair. I could have had almost anything even if my bet screamed flush draw...

The second time I had 109s in, again, spades. Again two spades on the flop and semi-heavy betting. I again push it all to the middle and get one caller. Only this time it's the nut flush draw who calls. For me this is an increadibly fishy call unless he puts me on a lower flush draw. I got lucky this time and hit a pair and the flush didn't come.

Maybe $25NL is too low to get any respect for this play? Or is it a bad idea altogether?