I have had MucOff corrode some finishes but still use it only very carefully; never leave it for long and use jet wash on low pressure setting to ensure it's thoroughly removed. Generally I think iot's okay on laquered or painted alloy surfaces but the alloy frame and top yoke on my old Gixer was left with loads of marks, you live and learn.

I also use Sdoc100 as in another post, works very, very well and I've never seen any corrosion or marking but it is 'kin expensive