First of all, methinks everyone here has given good points. And hilarious, and terrifying anecdotes at that.
On the effectiveness of the word 'creep', though;
I suppose because it's a word vague enough to mean almost anything from 'skulking around me and leering at me and just staring at me for like, 5 minutes while writing me poetry about my dead Irish-Japanese grandmother' to 'just not cool enough to pursue me, dude. Look at the mirror.' While being accusing enough to stop people back. You cannot abuse the word 'pedophile'. Or 'rapist'. Or 'abuser'. You can abuse the word creep. Voila.