You can see it just from turning the wheel to the stop.

An obvious visual check is the boot. If it's cracked, the joint is most likely bad, as the grease would have either washed away, been degraded by water, or had grit and dirt enter.

Otherwise, a worn joint can present a world of symptoms. From noise, to rattling, to... Well, nothing at all.

And I don't believe time has much bearing on the wear other than drying out of the boot. If the joint doesn't move (ie: parked), it's not gonna wear much.

That said, I've seen a bad Empi branded ball joint that only had 10k miles on it. And some factory joints go well beyond 100k miles.

 

factory ball joints will last ~5 years depending on the roads you drive and miles driven. If it was replaced with aftermarket I wouldn't doubt they are worn out already, a lot of bumps happen between 2-4 years.

 

In my experience the passenger side ball joint wears out quicker then the driver's side. I think this is probably because the wheel on that side is hitting more 'surface imperfections' on the side of the road - catchbasins and such.

 

The only true way to test a ball joint is to put the car on a lift and use a prybar to put a load on the joint. If it has play, it is bad. I've seen ball joints that are 10 years old that are solid with destroyed boots. I've also seen balljoints that are a year old with the boots in tact and they were junk. Same goes with tie rods.

The best way to test ball joints without a lift, and having a lift helps ALOT for testing suspension, is to get the wheel off the ground and alternate pushing on the top and bottom of the wheel on the side walls. If the tire begins to tilt one way or another, you have a very bad balljoint. Keep in mind, if you can move the balljoint by exerting less than 100lbs of force on it then imagine the amount of play on hard turns.

To test tie rods, lift the car off the ground and grip the sidewalls on the left and right of the tire and alternate force left and right. If the wheel moves very quickly with little force left and right you have a bad tie-rod.

The moral of this story is you really need a lift to check balljoints/tie rods. If you don't have a lift, trust your mechanic or find someone who has one. The other moral is just because the boot is torn on a joint doesn't mean its junk. It may deteriorate faster, however the play in the joint should be the final factor in decision.