Any change of noise when you depress the clutch at idle is a bad sign.

If you're buying a higher mileage one (over 150k) then I wouldn't even consider one that hadn't already had a new clutch/DMF and replacement injectors. At that kind of mileage big bills are potentially around the corner, so you could be buying a world of pain.

I'd rather buy one with 190K on the clock that had had recent injectors and DMF, than one that had done 90K and was on the original components.

They're excellent cars when they're working, but pure evil when they go wrong.