Fairly simple to check king pin play. Most shops will place something under the lower control arm and compress the spring a bit. This will take the tension off the upper control arm and if there's anything loose, it will really show up.
As a more basic test, I push on the top of the tire and pull on the bottom in a rocking motion ( car is on hoist ) to see if I can feel any play. Any play at all will show up as king pin wear, loose wheel bearings or pivot wear. To isolate this a bit further, I grease the front king pins and try the same test again while watching for movement. If the play goes away it's likely to be king pin wear. If it doesn't go away, it's more likely to be loose wheel bearings. You pretty much need to compress the springs to check for upper or lower pivot wear.
Tie rod wear can be easily checked by pulling on the back of the tire and pulling on the front in the same rocking motion as checking for king pin wear. In this case you are appying load in a different direction and any play will show up as excss movement at the tie rod ends.
You need to check both sides of the car and pay extra attention to the front right looking for idler arm bushing wear. This will present as up and down movement of the idler arm as you push/ pull on the wheel. Idler arm bushing wear will result in a lot of bump steer as you enter a long sweeping curve such as an entrance ramp. All of the load will be on the left front while play in the idler arm will steer the right front tire all over the place. If you find that you're constantly correcting during these conditions you should have your front end checked for wear. Of course, other components will make your car feel loose because of the constant loading and unloading of the steering gear while a front end in god condition will alwas feel secure.
