The Sherlock Holmes actor explained that he can tell when some men have clearly taken ages perfecting their style.
"I love the ritual of getting ready for an event, but you can tell when a guy has been standing in front of the mirror for too long," he told Glamour.
"Over-trimmed beards, over-styled hair, perfecting a look for hours and pretending it's effortless - do me a favour!"
Speaking about his own usual grooming routine, he said: "My routine is shower, aftershave and, until, recently, trimming my beard which I had for nearly a year for Anna Karenina."
Law added that different film projects give him license to try out new looks and styles.
"Having a moustache and sideburns as Watson in the Sherlock Holmes films forced me to try new clothes," he explained.
"Jeans and a leather jacket didn't look so good anymore, so I bought a corduroy jacket and big snuggly jumpers. Suddenly, they looked cool."
Jude Law is currently filming Stephen Soderbergh's latest film The Bitter Pill opposite Rooney Mara.
He is expected to reprise his role of John Watson in a third Sherlock Holmes film.