I know exactly what he meant. Pressly is the embodiment of sexiness, but there is something just a little hard and cheap about her. I have no idea what she's like, so this is of course unfair, but she looks neither intelligent nor soulful.
To be a ten, a woman has to present the illusion that she is good, and kind, but maybe still has a naughty side. Perhaps more than anything else, she has to give the impression that she is smart enough to appreciate you. She must appear, somehow, better than other people -- not just better-looking.
Mischa Barton, when she first appeared on the scene, presented that illusion:
Barton looks as if she's capable of the full gamut of emotions, including sadness, whereas Jaime Pressly always seems to be wearing a half-sneer that said, "Let's par-tee!" (Pressly's expression, in a weird sort of way, sometimes reminds me of Snoop Dogg's.)
Donna Reed was good at presenting the required illusion. Even in middle age, she was capable of projecting a sort of Glinda-the-Good-Witch level of benevolence:
Yet when young, she was also capable of sultriness:
And of projecting a sort of worldly, skeptical, even rebellious intelligence:
I guess the point I'm trying to make here is that it helps anyone's looks if she can make it look as if there's something behind her magnificent facade, even if there's not.
I'm not even sure I agree with my son about Pressly. And I'm guessing that had he seen her in person, he'd have felt differently. But I understand his hesitation.