When I or another MM post an order it is priced off basis, options synthetics, constituent portfolio, a similar asset or any other source that let's me calculate the no arb/fair value price of the undelying at that precise moment. When I get filled, it was either another shark who is faster or hast a better pricing model or it is a customer (you) who makes a trade based on a mumbo jumbo assumption or because he invests in his 401k and doesn't care. Flow of other sharks is called toxic and I want to avoid it. Your flow is called uninformed since you literally don't know fair value and I want as much of it as I possibly can. For example, I would pay your online broker a fee so he sends your order exclusively to me. I would be the only one with access to your order and it would be free money. Problem is: I'm not licensed to do that. Guys who are, call that payment for orderflow and its regulated under Rule 606. When it's mumbo jumbo to you, you can safely asume that you have no clue and there is more for you to learn.