Some say it's useful, others say it's not.
You can see most days that large players spoof the DOM. As such, you have to wonder WHY they would do this. Perhaps it is for the pleasure of pulling large orders. Perhaps they have a reason for doing it.
If you believe the larger players spoof the DOM for a reason, then it follows that some poeple are falling foul to their activities. It also follows that a small player with a little knowledge of the games being played can make some money off the back of their activities.
I think Edward De Bono has more answers that Alexander Elder ever did in terms of looking at this type of activity though.