Honestly, I would say any fashion show is off for young girls. The constant makeup on everyone, including the 14 year old Kylie is not a positive aspect for young girls.
However, It does have a good message of family is important. Family should come before everything and if it doesn't, their is repercussions (Think Rob feeling outcasted and alone, Kendell feeling like no one pays attention to her needs about school,Khloe feeling hurt that she constantly has to be the parent for Kris, and so on. It shows that it can and will hurt your family if you let work consume you.)
Also the girl's have AMAZING work ethics and maturity. Kendell and Kylie, actually manged to take control of their education and switch to something that allowed them to work at their own rate and be successful, WITHOUT their parents after they failed to help them for two years.
The positive role models are : Khloe and pretty much her alone.
Violence : is rare, but sometimes there is throwing things. Rob went to the extreme and ended up in the hospital on the spin off show.
Sex : Sometimes references are made and dirty jokes, mostly from Scott or Khloe. Also some of their outfits for photoshoots and events are inappropriate for younger kids to see. But most of their around the house clothes are find (which is mostly what you see).
Language : it's bleeped (poorly). But d*mn it and similarly words are left in.
Consumerism : They mention their store a LOT, mainly because they are working business for it and moving locations and so on.
Drinking, Drugs, Smoking : Drinking is an issue. Kris (the mom) has gotten drunk quite a few times. Rob and Scott party very hard, and often it becomes inappropriate and very drunk.