a five-minute test to catch a repainting indicator

[Shadow Trader]

Some indicators rewrite their own past. The arrow that screamed "buy" three bars ago quietly vanishes, and the one that stays looks perfect in hindsight.

Here's a test anyone can run without reading code.

Put the indicator on a 1-minute chart in real time. Take a screenshot every time a signal appears, noting the time. Come back twenty minutes later and compare the screenshot with the live chart. Signals that moved, disappeared or appeared in the past are repainting.

A second check uses the bar currently forming. Signals that flicker on and off until the candle closes are not necessarily dishonest, because they're reacting to an unfinished bar. They just can't be trusted until close, and an entry taken early is a different trade from the one the history shows.

Zigzag-style tools and anything that picks swing highs and lows with a look-ahead will repaint by design. Many "no-repaint" claims in sales pages only mean the arrow stays once the bar closes, which is a much weaker promise.

Another sign: a backtest screenshot that shows entries at the exact tops and bottoms every time. Real signals arrive late, so a result that perfect should raise eyebrows.

Reloading the chart or switching timeframes also redraws history, so a before-and-after comparison of the two views tells a lot.

One more: a tool that looks flawless on the last 500 bars but messy at the right edge deserves suspicion. Real signals look ragged in real time, and only the rewritten ones look clean in hindsight. Paper trading the signals as they appear, not as they sit in history, gives the honest answer.

Which indicator did the most damage before its repainting was spotted, and how was it caught?