I would really support an agency that made a commitment to putting a date on their pictures and updating the pictures say every 3 to 6 months. It has not been a horrible problem but quite often, unless the girl is brand new, the pictures are from when she started working. Which might have been years ago. Hair color and weight often change.
Some agency's do seem to be better about updating the ages as well these days. The trend before was to perpetually leave the girls the age she started.