I've let my 10 year old watch it. There is a lot of innuendo, plus the maid in her costume, plus the scene where they are all pretending to make out to throw the cop off the trail, plus the blackmailing involving Miss Scarlett and her house of ill repute. We love it and quote it often.
We have it and DS12 has seen it multiple times and he isn't too scarred. I think most the humor in it is over their heads, or at least I know I didn't get it until I was an adult.
I remember going to see it in the theater with my 2 cousins (one was 12 and the other about 16) and based on when it came out I was evidently 10 at the time. I know at the time I didn't notice any of the innuendo in the movie and it wasn't until I watched it again years later I "got" it.
DD13 has seen it several times over the past few years. we have it on DVD. i don't recall any bad language, just LOTS of innuendo and, as a PP said, there was some fake making out.
I first watched this when I was about 8 - I recorded it off TV but it got wiped over when I was 10.
I didn't see it again until I bought it on DVD aged 23 and it was only then I got the jokes and innuenedos, plus actually knowing who J Edgar Hoover was.
My sister and I have entire conversations using only quotes from this film...sad!
I remember my aunt taking us to the video rental store called "Movies and Munchies" to rent it when I was young. I was probably ten at the time too, back then, I honestly thought it was kinda boring, but now I love it.