Check out the thread under beginners for details of how to wash your mirror. Good news is that aluminium doesn't go mouldy; the crap on might... give it a wash and some TLC.
Hi Rob,
Just cleaned my mirror - it was very dull looking, not mouldy.
Washed it in soapy water and the gunk disappeared immediately.
Check out attached doc for tips in Beginners Start Here section
("Cleaned my 12" mirror tonight" thread)
Cheers
Doug