They're often called "Prize Pigs", who simply want free stuff, because they can get it. No rhyme or reason.
The one local radio station I listen to, the morning DJs were talking about some the other day, where the lady doesn't listen to the radio station (I guess just finds out about contests from the website) and won Blues hockey tickets. At the game, the lady sat next to the DJs, and the entire time was pestering the DJs pictures of her dogs, and not paying attention to the game at all. She obviously had no interest in the tickets, so why go for it?