Hang them outside on a sunny dry day. My husband's aunt had a house that reeked of mothballs. She thought they would keep insects and spiders out. I got physically ill every time we visited her.

Do you think it could be something other than mothballs?

I have some black jeans from LL Bean, and my daughter has some gray jeans from Target that both have an odd smell. They have both been washed many times with no improvement. What color are your daughter's new jeans? I was thinking it might be something in the black/gray dye.

Charlies soap or add vinegar to the wash

This may be too late, but I had a somewhat similar problem this past summer and came across this product http://www.scoe10x.com/scripts/prodView.asp?idproduct=18

I did not actually get it though. In my case, the problem was an old coat from my MIL. It stunk like mothballs so I foolishly washed it with a load of other clothes. It made the entire load smell. I left the coat in the sun for days with zero impact, I gave up on it. However the rest of the clothes were pretty much back to normal after two or three washes with vinegar.

They are regular blue jeans. I've noticed that odd smell with black jeans too.
I soaked them in water with vinegar and oxyclean. Then washed them again and sprayed them with febreeze.
They still have a faint smell but it's definitely better. I'll try hanging them outside on a couple of dry days.
Thanks for all the suggestions.

I got some clothing like that and I supect it is some kind of pesticide. I just kept washing and after 6-8 washes the smell was gone but it makes you wonder if they are safe.

Chinese factories like to play tricks on the manufacture of products bound for America.
I have shirts that first wash the buttons, every one of them fell off.. no sign of threads at all after the wash. They have an odor still after many washes. Odd materials used that some USA educated grad student now working textiles in his home country china substituted on the specs. They couldnt get the specified materials or just cut corners.
Funny haha, and saved some money on that contract - they won't know.

Fabric softener is the key to get out funky smells in clothing. Run your wash as usual and set it up with liquid softener. Works like a miracle.

Wouldn't that just cover the smell with another (worse) smell?