LB, I believe it is generally accepted that the only "Approved Shoes" are RM Williams, they must be Black and always shiny, not more than Size 8, anything larger may cause fowling when using the Rudder Pedals and general perception of "Over Compensating", failure to comply may result in 50 Penalty Points and as always Strict Liability applies.
It is up to the CASA Inspector to determine if your shoes are of a "Shiny Enough Quality", if the day is gloomy and there is insufficient Sunshine around to make your RMs properly "Shiny" this is your fault and will not be taken into consideration by the CASA Representative, Airline Pilots will of course have the benefit of Airport Lighting at all times, GA Pilots are buggered and should have stayed indoors until the sun was shining outdoors.