Only in the same way that you can guess the nitrogen content of the air in the tyres by looking at the headlight bulb.
Actually not quite in the same way huh. You've no access whatsoever to the inside of the tyre from the headlight bulb.
I was thinking more like visually checking brake pads without removal.
It was a silly question (although no question is silly) I know partly born from a bored moment but you can actually see/reach some of the plates from the filler hole. So if the was considerable wear would the spacing of these plates in theory be Feeler gauge noticeable.
Either my clutch is on last legs or cable has stretched and needs renewing but if I change the cable am I then risking over wearing the clutch too far and foccin up the flywheel Blah blah
Obviously the only sure way of knowing the clutch condition is by removal and measuring individual plates but that means £16 for a gasket and the clutch then may as well be changed.