It will depend how worn they are and where they're worn.
When our first set went (the OE audi ones) there was no obvious symptoms, i was jacking the car up as i suspected a front wheel bearing was on the way out (it was howling a bit), and noticed a wobble in the wheel. Investigated and the top two balljoints were gubbed. The bearing was gubbed, but there was no detectable play in it.
I then fitted ebay-povertyspec arms all round. After about 2 months these started creaking and groaning when steering, espeically low speed car park type manoevers. The car then developed a really horrible vibration, felt like balancing but you couldnt pull thru it, it just got worse as you went faster, by 85 it was trying to pull the steering wheel out of dawns hands. Investigated again, and again the balljoints on top arms were dead, even moreso than the audi ones i'd removed only 4 months previous, but this time, they'd allowed enough camber and toe change to wear the tyre egg shaped on the inner edge. Presumably the vibrations were the control arms moving around and some kinda resonance occuring.
After replacing the arms it totally transformed the drive though. Car felt stiffer and more precise. Its on Meyle arms now.
Its probably worth looking at the rear bushes too, as at 10years old they will be past their best. Changing the rear axle bushes on ours changed the drive so much that it felt like the car had been lowered/stiffened up, even from the passenger seat!
As for the AFM, i cleaned mine with a blast of carb cleaner, although some say to use "electrical contact cleaner" instead as its less harsh.
