That is not true.
"If you bid 20 and your turn is up and the ask is 17, you are still paying 20, along with trade fees, the spread between bid and ask is brokers profit, you don't think they will jump at the chance to sell to you for 20 what others buy at 17?"
I have never had this happen to me. I have always been filled at the best available price and a few times even on the bid. Same goes for selling. Of course when you are back in the line the price may move but when your time is up it is best available price. Yes of course I have seen a few times poor souls get filled way above or below the current bid and ask. IMO it is a rarity and not the norm. It may also have something to do with the way the person entered the order such as AON.
Also when you see a ticker with quite a bit of volume you may see a few outside the current B&A. Often it is just a late reporting trade as brokers have I believe 5 mins to report after which time it must be reported after hours as a T trade.
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