DIY lower control arm Video
 

These are very common to go out. Its even worth the cost of just buying a new arm rather than the bushing and pressing it in!

I mean, if the ball joint checks out you are just spending extra money.

Sort of yeah, but a ball joint that's got 80k on it will "check out" and probably start to fail within another 20k miles. Would you rather replace it now while everything is disassembled or wait for it to fail and tear everything apart again.

I have this discussion with myself every time I start disassembling parts on a vehicle, personally I replace a LOT of stuff BEFORE it fails just so I don't have to keep taking things apart. Many factors play though, do you have access to a hoist and all proper tools making for speedy repairs, do you have a lot of spare TIME, do you have the extra MONEY, etc.

Both sides are valid arguments depending on the perspective.