You can be effective at selling opiates to people, but then end up in an investigation for selling them illegally and thus neutralising any of the revenue you had initially brought with fines for doing so illegally. Here's no effect.

Of course a lot of brutal strategies work well in environments which do not expect them. However trusted environments are often more efficient.

With a comma? Ineffective doesn't mean no-effect, it means 'not the intended effect'.

I.E. "McKinsey worked with Purdue to implement an ineffective business strategy that resulted in bankruptcy for the business, due the harmful nature of the product and the predatory nature of the strategy."