The star, renowned for the way she seems to purse her lips in photos, said that her mind was elsewhere most of the time she was having her picture taken.
Appearing with Whoopi Goldberg and other hosts on US show The View, she said of her pose: "I just think that's just me. Maybe it's the way my face falls, I don't know."
The singer turned fashionista added: "At the end of the day I do what I do. Half the time I'm just doing it, thinking, getting it done, sorting out the kids, you know."
Beckham also said she was sick of being considered the "funny" one in her marriage to David Beckham.
"Everybody says 'David's so handsome and she's so funny' - I'm sick of being the funny one," she said.
Asked if she still felt sexy after 10 years of marriage, she answered: "Yes I still feel sexy. We're so lucky to have each other. I really feel that with David I've met my soul mate. He's a really amazing father and a really great husband as well, yes I still feel sexy.
"I go to bed with David Beckham every night, I'm trying."
The former Spice Girl, who was wearing one of her designed dresses in grey and matching towering heels, also told her secret of looking so good every time she is photographed at an airport.
"I think it's the way I was brought up ... when you travel you always look nice.
"I always have a tracksuit or my pyjamas in my bag, so I go into the toilet - I'm a bit like Superman when I get in there, I put on something comfortable."
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Beware of spending beyond your means. Sticking to a budget will help you survive the festive season relatively unscathed. It will be easier than you think to let your grip on the purse strings slip especially as the big day draws near. Let Christmas be about loving, sharing and giving. Spend quality time preparing food, making decorations and playing games together. If you haven't sent all your cards or round robin emails give some thought about what you will be sharing with others this year.More