As you say, 끈적끈적거리다, 끈적끈적하다, 끈적거리다 all mean "to be sticky". It's also used to describe an attitude overly obsessive or aggressive toward someone else. Here's an example from a novel: - 우리에 대한 엄마의 끈적끈적한 집착에 넌더리까지 났다. => I got sick to my stomach of mother's obsessive attention over us.