tl;dr: never underestimate "reader's tacit or criminally negligent acquiescence."
'If you honestly say: "This is good with <product>, this is bad with <product>".'
In order to evaluate the veracity of the claim, you have to try the product. And if you have to pay money to try the product to verify the claim, then it's unclear as to how many people will actually bother to verify. If you price it high enough that the number of people is zero, then you could say whatever you want without others knowing if you are being honest.
'If you honestly say: "This is good with <product>, this is bad with <product>".'
In order to evaluate the veracity of the claim, you have to try the product. And if you have to pay money to try the product to verify the claim, then it's unclear as to how many people will actually bother to verify. If you price it high enough that the number of people is zero, then you could say whatever you want without others knowing if you are being honest.