I wasn't sure whether explaining the falicy in reliance upon scanners, not as a trading methodology, but as they are represented and marketed, and then excused by the lenghtly worded contract as just that, a falicy.
yes, scanners, in general do scan... however, whence sniping trades and the like, as pro's do, usage of a scanner frees up brain clock cycles and relocates them to the desktop. Many traders, that I've observed, cursed the day that they lost control of their decision making processes to a scanner, whether ESP, the other one or First Alert or otherwise.
Frequently, just watching CNBC or CNNFn will do the active scanning function in a manner that is more sureal and provides at least fundamental news backup to the assertions that a particular stock is worth intraday trading.
I fault the dualilty of the scanning software craze, and especially ESP as it is one of the foremost in complexity.
Whence I monitored it in real time, it would frequently notify me of far too many trades, even whence I slowed down and narrowed the search bandwidth to just, say, 12 pre-sets. Even then, the T1 bandwidth and software of the charts were too slow to jump over to the stock that just flashed on the trigger.
1) Given that the event has to occur first, then get noticed by the screening software on the server side, and then be placed and categorized in its trigger pattern (incidently, one event can be categorized in numerous trigger pattern events)
2) your connection speed and subscribe portion of the publish and subscribe equation has to receive the notification that an event has triggered
3) you have to watch for each new entry on the notification list
4) adjust your screening software and charting software to go observe the chart, make allocation decisions and finally a Buy/ No-Buy decision
The problem with these scenarios is that these software Screeners have -2min predictive abilities. If these are trend followers, as such, then following an existing event (by definition being a one time event) is not the same as Momemtum trading (essentially following a trend).
Trend following screeners would be more profitable to most traders and less suspect to market manipulation even during violent trading periods.
If my thesis seems logical, then let the chorus sing....