
Cover/hide a multitude of sins
Positive Distraction
The phrase often implies a notable quality compensating for other issues, drawing attention away from negatives. 
Figurative Usage
The 'sins' are not literal but figurative, often referring to faults or mistakes rather than immoral acts. 
Idiomatic Nuance
The phrase adds a humorous or light-hearted tone when acknowledging someone's shortcomings. 