Quote from FXTraderWill:
I can figure it out even though eSignal cannot, and when I can't distinguish between a trade being on the bid or offer (which happens very rarely). I make at least 70 trades a day and that hasn't happened more than two or three times in the last few weeks - by "that" I mean watching the tape and not knowing if liquidity is being taken or added in a spot where it's crucial to know. I can buy or sell 100 shares to see where I get printed to test for hidden liquidity if it's necessary, which it rarely is, and if I really must find out if the tape is green or red, it's not because I can't piece together the quote and print feed since I remember every movement of every price level on every book - it's because people are being sneaky withi hidden orders, or putting in algos that will sit at a price level and automatically sell at any any bid that comes in, even though it's effectively an offer being hit, the prints would be red. But I might know when it's effectively a green print since people put in bids knowing they'll get filled, and they want to test the reserve of the seller's willingness to leave his algo on to smack all bids. Watching this is tape reading.
When there's a buyer in a stock and there's momentum and I see how people will get squeezed and can react first and take an offer in that sweet spot and trade the position well. When I read the tape, I can find the confidence that the stock has a buyer because I can feel the buyer, and even if I'm wrong my risk can be minimized because I am able to accurately estimate what kind of slippage I will suffer if I am wrong before getting into the trade - knowing what my realistic risk and reward are at a given point in time, knowing how likely it is that I am right on a trade, and knowing when I don't know anything and have no edge and hus I should stay out, as well as when I should size in because the reward might be worth it and I need to take all the precious liquidity I can. So tape reading isn't lost and just because you can't figure out if a trade is on the bid or offer even though there is a constant lag between the print and quote feeds(if you peace things together it makes sense unless thest stock is cluttered with useless noise, in which case tape reading will be much more difficult and you should find something else...) - if there is a buyer or a seller in a stock who is aggressively working his order the tape will always reveal high probability entries, it's up to each individual trader to be able to recognize the setups, not hesitate, and trade them in a disciplined dway. The discipline is much harder than actually reading the tape IMO.