[Cooker]

I suppose the thinking might be that extremely weak draws like backdoor flush and runner runner higher straight draws will fold to any bet while they can conserve money if the board pairs on a later street. Still, this motive is probably too sophisticated for typical fish which are probably thinking more along the lines of "I always get drawn out on, so I don't want to put in too much money." All I have to say is you have to love this kind of fish that never charges you to draw and always pays to draw to his flush.