Front Passenger Grumbling Noise
 

I bought a used 02 S60 in March and ever since I bought it, the front passenger side of the car would make a low grumble/vibration type sound for about a second after driving over bumps or manholes in the road. I've had the car inspected before and also serviced at 105k. No one has ever mentioned that something was wrong. The sound was getting worse so I took it in to the dealer today. They said the ball joint needed to be replaced, so I gave them the go ahead and paid $215 for it. Right after driving it out of the dealer it was still making the same exact sound. After calling them they said it might be something vibrating under the hood of the car. If that is true, I'm wondering if the ball joint really needed replaced. Isn't that something they would have noticed during an inspection, alignment, and a 105k service? Any ideas what the sound could be?

Yep,
In reality any shop would have probably taken your money and maybe thanked you, that's about it. Ball joints rarely cause vibration they more often cause a clunking metal on metal kind of noise and they do sound scary enough to drive you to the service station. Try getting under the car if you can (obviously secure the tires yadayada) or stick someone else in there and have them move things around like the plastic "skid" plates, exhaust etc. If you hear a sound similar to what you heard before, you found your problem.