Such a claim needs evidence; by its nature, it insulates itself from counter-arguments based on experience.
If person X says "ads don't work on me", the state "I experience no influence from ads because they don't work" is indistinguishable from "I experience no influence from ads because they're so sneaky that they only affect me subconsciously".
Unfortunately, it's very hard to get individual-level evidence. You can get population-level evidence, but sometimes that evidence shows that the ads don't actually work (for instance, The Correspondent's 2019 articles about the subject).
If person X says "ads don't work on me", the state "I experience no influence from ads because they don't work" is indistinguishable from "I experience no influence from ads because they're so sneaky that they only affect me subconsciously".
Unfortunately, it's very hard to get individual-level evidence. You can get population-level evidence, but sometimes that evidence shows that the ads don't actually work (for instance, The Correspondent's 2019 articles about the subject).