Different people have different notions of sexiness.
A girl may be sexy to a guy when she is confident/sexily
dressed/flirtatious in behaviour/has the looks/is in the mood.
Beauty, and sexiness, is in the eye of the beholder.
Telling someone that a "dao" girl is sexy is like saying that an
apple tastes better than an orange. People may agree or disagree
with you, depending on their taste buds. Naturally, the presumably
unattainable is more desirable, and that factor itself contributes
to how you feel about the girl.
If you think that your girlfriend is not sexy enough for you, you
can always communicate your preferences to her in a nice way. But
you are certainly not asking her to be "dao" to you, right? Well,
you can ask her to dress more sexily, if that's what you
want.
For me, a "dao" girl is more of a put-off, although there are
exceptions. I am definitely more attracted to girls with warming
smiles and friendly dispositions.
