The expression is talking about blushing, or how some blush when they lie.
The reality we all know now is of course they did it. They are trying to
ENOUGH IS ENOUGH! We were not born yesterday. We have seen plenty of psychopaths and are getting to know their tactics really well.
She can lie without being the least
Also, the irony is that my ex who taught me the expression "You do not have blood in your face" is also a raging psychopath capable of lying with no effort or remorse.