My ZX10 used to keep getting an advisory on a notchy headstock, which I could never feel. Ever. So I never bothered replacing it (it's a shit getting the old bearings out of the frame on a bike).
Until it failed its MOT one year. I couldn't feel it, so I took it home and got various bike mates to try it, and they couldn't find anything wrong. So I took it back and spoke to the tester. He remembered and said it was really bad, and invited me to hang on until he had finished the current MOT, then he'd show me. On his steering plate it was clear as day that the bearings were shot, even though riding it felt perfect, as did trying it with and without load on it.
The point being, there are scenarios that can show up faults that otherwise are impossible to see. So if in doubt, have a friendly word with the chap, and see if he can demonstrate, even if it costs you a drink or 2.