I met a man, a very wealthy man, several years ago. He told me of a program callled a 'snake,' which was designed to execute orders with typographical price errors if they were favorable. It just went out and looked for them.
I used to notice on isld after hours, as soon as I was high bid, someone would join me -- instantaneoulsy. When I cancelled, he was gone. One night I called isld and asked one of the techs. All he would say is, 'Oh, sure...I don't doubt that someone would write such software.'
What you describe is certainly possible, though diabolical. I suppose someone will defend it. It is uncanny sometimes how the posted prices and sizes seem to be immediately affected by my orders on some of the secondary, less active issues -- the ones that don't have alot of followers (then too are the times when those orders are completely ignored, owing to the 'free time' loophole).
If you search, you'll find some things I've posted about specialists ignoring DOT orders -- documented and proven by one of the institutional investors in ARCA (American Century Ventures). One of the big battles is forcing NYSE to honor ITS-CAES orders (which they apparently haven't been inclined to do).
With ARCA being designated the nation's first electronic stock exchange, this apparently will have to change (unless inca or someone buys them and shelves them...but I don't think it'll happen).
I'll just attach that article again. It's well worth it and might give pause to the more thoughtful of the apologists for the NYSE who say things like 'life isn't perfect, if you don't like it, go somewhere else.'