I colored my hair with L'oreal's Castings Creme Glos hair color. The package says: "Lasts 6-8 weeks".
I noticed that it doesn't come out of my hair. Then I called L'oreal's customer services and they confirmed it: It is a permanent hair dye.

Now I have ugly hair and nasty looking roots and it takes about five years to grow my own hair color back.

I think L'oreal has lied to me. And it just makes me sick how some people at message boards give good reviews to this cheating hair dye (I wonder who pays them to do so).