The 42-year-old "Lost Rivers" actress said she gets more compliments on her full head of long brunette hair than on anything else, reported US magazine.
"I only wish I had never bleached my eyebrows," Mendes said.
The actress, who just had her second baby with husband Ryan Gosling, said her favourite cosmetic is a good concealer.
"A good concealer can do more for your complexion than double-sided tape," she said.