First, thanks for your lively appearance on the D/T thread. Don't usually read it until the evening but when you sprang up couldn't help but think your addition really brightens the tone.
Re NEVER BUY A FALLING STOCK - this one has always confused me. Yes, reckon it's broadly true but sometimes when a stock suddenly does a wild fall south, really sharp and steep on a chart, you can get a stupendous bounce. There were lots of examples of that last week. Maybe it depends on the situation, the stock and also, perhaps, knowledge of resistance/support levels.
If you buy a stock and realise that it's about to fall further you should use the TWO PERCENT RULE (as Gizard has called it) and get out as soon as possible.