Everyone has some good points.
I think that as long as one tempers it with other age appropriate clothing it is fine. Juniors clothes tend to be made of lesser quality fabrics and of very trendy styles, but like everything else, if you choose carefully, one could incorporate something into a total outfit, I am sure.
Like Katherine said in her book, only 30 % should be trend driven…..I do also believe the adage that the older one gets, the classier the clothes should get. If you are talking things like T-shirts or button down shirts, you’re fine at any age - as long as there are no crazy sayings on it, I guess ( Confession #1, I have a Freddie Mercury t shirt that I love to wear under a very tailored blazer - I am 45 ).
But I will take it one step further, though I am 5’6’‘, I wear a size 2-4 top ( I got the man-boob thing goin’ ), so I can actually wear CHILDREN’S clothes in 12 to 16 ( YIKES ) !!!! ( Confession # 2 )
Yesterday I scored a skinny stripe , stretch T shirt at Target in the little girls’ department for $3.00 !!! I wanted one from Boden but I couldn’t justify the price. So as long as I don’t wear with my Hannah Montana jeans, I should be ok, don’t you think ?????? LOL