Tubbs,
I don't believe the order book to be a "red herring" at all. There are a great many things you can learn through watching it. Does the size disappear when a bid/offer gets hit/lifted? Is the size still there when the market trades away and then comes back? I watch the ES DOM rather than YM simply because it's mainly that which I trade and because I find the big numbers easier to follow than the small ones on the YM DOM, e.g. I find it a lot easier to spot the habitual 1000 lot spoofers.
All of the practices that Frugi pointed out can be observed if you watch the DOM with an idea of what you are looking for. However, ss Rog pointed out, you have to get beyond the obvious...... if there is big size on the bid/offer and it's posted by a limited number of market participants, it's there because someone wants you to see it............
I tend to have an different view about the reasons the markets move to size (but that's what makes the markets go round). I believe that the majority of the time the motivation for doing so is so that the size can be leaned on rather than bought or sold.
Hmmm, not so sure that "spoofing" per se, is a valid indicator of anything. Order flow, on the other hand........
I think you need to develop an awareness of "price discovery" through T&S, i.e. why do certain price levels attract more volume that others?, before trying to extract anything of value from the DOM.