The hotter the babe, the more she has been approached, the more she is tired of lame pickup lines, the stronger the shield against casual approaches, the more the skill you’ll need, the less attached you have to become to the outcome, hence greater the need for unusual approaches.
In other words, if she is really hot, then casually walking up to her and saying “Hi” will not work as effectively as walking upto her and saying “You need to smile more, nobody will talk to you otherwise”.
Hotter the babe, riskier the approach.