I hear "they wouldn't do it if it didn't work" about many dark patterns. Is there proof to this? I suspect that these kinds of things are easier to measure than

I hear "they wouldn't do it if it didn't work" about many dark patterns. Is there proof to this? I suspect that these kinds of things are easier to measure than less aggressive tactics, leading to a false sense of efficacy. And what of the efficacy compared to the negative reputation gained from such practices? How do they measure that?