There is a downside to being a “Twilight” heart throb. Hot actor Kellan Lutz had to don a black wig and hide under a hoodie in South Beach the other night. After attending a Phish concert, Lutz, who’s been dating “90210” beauty AnnaLynne McCord, tried to go incognito while partying for hours at the Delano’s Florida Room. But a spy said, “The disguise didn’t really work. He was getting lots of admiring glances from women, but he only seemed interested in hanging with his friends.”