polohat,
Super Signals was an indicator created to show "the future", it would read the bars of a chart, and give signals to make it look like they were "super".

example:
Bar -1 = upcoming bar.
Bar 0 = current bar.
Bar 1 = previous bar.

If an indicator looks for a sell signal on bar -1, it is effectively looking for nothing in realtime (the next bar hasn't even opened yet).

An indicator will run this sequence for every bar formed. So, if you have a 1000 bar chart loaded, it can look for "signals" from 998 bars.

Like an exam, if you already know the answers, its easy to cheat

a repainting indicator "cheats" and changes its response after more time passes (and more bars close).
If you sell as soon as you recieve a sell signal, a signal to sell 3 bars ago is not very helpful.

I hope this explains.