Everything about Arnold Friend's appearance is contrived, faked. His look, his hair, and even the way he talks are all a performance. He's created this persona in order to seduce girls. It becomes clear that Arnold and Ellie are both much older than Connie. Therefore, Arnold must act and appear younger than he is in order to appeal to Connie. Part of that is his physical appearance which has similarities to the way Bob Dylan looked in the 1960s. He is described as having shaggy black hair and wearing sunglasses. This is not to say that Arnold is similar to Dylan. Arnold was trying to look like Dylan (or a similar rock and roll star) in order to appeal to a younger Connie. Ellie listens to the same radio station as Connie. It is Bobby King, also a reference to Dylan. Also notice that Connie thinks his shaggy hair looks like a wig, another indication that Arnold's entire persona is constructed.
Arnold (and Ellie) use music to connect to Connie. Music becomes a unifying component among the three characters. Despite the fact that Connie feels threatened, the music gives her a familiar feeling. So, there are, for Connie, feelings of danger and seduction associated with the music. Although Arnold may be seen as a symbol of evil, one could also see this event as one of Connie's "trashy daydreams." And in the case of the latter, the story is also about the seductive power and rebellious draw of rock music.
There is another reference to Bob Dylan's "Mr. Tambourine Man." One of the lines from the song is, "Take me on a trip upon your magic swirlin' ship." There is an allusion in "trip" and "drug-induced trip" and a song as a "trip" all of which connects with the trip Arnold wants to take Connie on. A lot of Arnold's speech sounds like he's memorized song lyrics.
Don't hem in on me, don't hog, don't crush, don't bird dog, don't trail me," he said in a rapid, meaningless voice, as if he were running through all the expressions he'd learned but was no longer sure which of them was in style, then rushing on to new ones, making them up with his eyes closed.
Arnold uses music and this contrived way of trying to sound like a lyricist to connect with and seduce Connie. He is like a siren or a snake-charmer. He is like the wolf in "Little Red Riding Hood," using a disguise to trick a young girl. Music and lyrical allusions are part of the disguise.