When we see quotes in bid/ask, there is something not show. I have got prices better than the bid/ask, that is, between them, with no delay. For example, when the bid/ask is 3.2/3.5, as soon as I transmit a sale order limit 3.25, the order is filled instantly. There seems to be a limit buy order, invisible, for 3.3. The invisible trader has an advantage over the public. Is this true of your experience?
Yea hidden orders are nothing new. I can do them from Lightspeed and Redi among other platforms. So you're getting hit on hidden orders... no advantage. I frequently put a 43.0203 limit order, so step in front of the 42.02 bidders. There's no advantage though.
Your 3.25 offer might facilitate the fill of someone else's spread order that's cts away from a fill... or it could be 10 cts away and the MM is taking a nickel off the other side as well, etc.