C-flat - your post reminds me of a stomache-turning incident where a fond karaoke-running father allowed his two very young girls (probably about 7 & 9)to sing that aweful song that went "lets talk about SEX baby, lets talk about YOU and ME". It was just so blatantly a "shag me" song and I felt it was really inappropriate for little kids to sing it. This was at a local fete, and of course the kids got huge applause & most people seemed to think it really cute.
Having said that, I totally agree with Liz that you can't partition your children off from the world that their contemporaries inhabit. I think the best you can do is to try to give them self-confidence to think for themselves rather than follow the lowest-common-denominator media-led fads. They need that confidence to "dare to be different" - we can't change the environment they have to live with, but we can equip them to deal with that environment and to think for themselves. One of the most important things is that they should have strong role-models - to give them something better than a body-rubbing Britney to emulate! The folk world is full of strong individualistic people, so there's a good place to start...
Above all, teach them to laugh at crap pop pap. :>)

Kris