I feel like I see more rat traps than I do rats in LA, usually along alleys.
But I have seen some rats over the years, mainly in downtown LA's older sections or the Arts District.
Where I live in South Pasadena, I'm more apt to see raccoons, possums, skunks, squirrels, coyotes, parrots, peacocks... I live near Garfield Park, and I also live near a wash that forms a border between the cities of South Pasadena and San Marino---coyotes tend to wander along washes and riverbeds, so I've read. About a month ago, I saw what I presume was the same coyote walking down the street 3 days in a row, on my morning drive to work.