How would one distinguish love at first sight and lust?

An ancient statement such as "Love at first sight" doesn't ring true to me at all. Perhaps there may be experiences that blossom the growing flower of friendship into love, in which case I could see "love at first sight of the many good deeds and personality traits this person has" but truly seeing something as elusive as love and mistaking lust for love seems extremely likely. Romeo was easily smitten