If the existence of liars somehow calls into question the very existence of the annulment process, then it must call into question the existence of ALL institutions and processes, such as civil courts, that involve the testimony of witnesses.
Some who know, with 100% certainty, that their previous marriage was NOT sacramentally valid resist or avoid the formal annulment process due to the instability of their previous spouse.
And these people HAVE NO VALID IMPEDIMENT TO REMMARIAGE!
However, the self righteous seem to have no problem with the phony, fraudulent “annulments” granted to people who did not deserve them. (The Kennedy family comes to mind).