As a private citizen with no interest in "currying" a fanbase, I can afford to conspicuously display skepticism and ask, e.g., a person claiming to be a disabled veteran some
pointed questions or even outright demand that he present his
credentials. If that person gives a reasonable answer, but still doesn't seem quite "legit" (i.e., my BS-meter is running wild), I might continue conversing with him, but I will remain cold and distant. I will not, e.g., volunteer any information or do anything to keep the conversation "running."
Someone in the public eye - and especially a "celebrity" - doesn't have those options.
Politicians and other celebrities aren't necessarily "dumber" or more gullible than average Joes - but they can't afford to be seen (especially on camera) as being uncharitable or unfriendly. Hence their vulnerability to being duped (or at least to appear - to our eyes - of have been duped).
Cohen knows this about his victims, and exploits it.
Regards,