No, not simply by virtue of their being custody evaluators.
Sometimes custody evaluators and other mental health professionals give the impression (either deliberately or inadvertently) that they have magic, infallible powers of perception that make them able to detect lies at all times and in all circumstances. ’Tis not so. It can’t be so.
While custody evaluators and other mental health professionals may be better at detecting lies than those of us who aren’t trained in it, they can still be fooled and are regularly fooled because some narcissists (dare I say most?) are staggeringly good liars. No one is perfectly (or even all that consistently) able to tell when he/she is being lied to, and custody evaluators are no exception.
Utah Family Law, LC | divorceutah.com | 801-466-9277
https://www.quora.com/Can-custody-evaluators-see-through-a-narcissist-s-lies/answer/Eric-Johnson-311