-18% conversions from a signup form (test)

Michael Aagard decided to increase his conversions from a signup form.
He included the phrase “100% privacy – we will never spam you!” to reassure people that they won’t get spammed.
And his conversions skyrocketed, right?

No.

Actually they decreased by 18%.

Why?
People weren’t thinking about spam.
But this phrase reminded them about this fear.
And this fear paralyzed 18% of people about to sign up.

Looks like “No bullshit”, “No fluff”, “No scam”, “No [input here what people can fear]” is a good way to reduce your conversions.
Do you have these phrases near your CTAs?