Thongs are fine as long as the rest of the clothing is neat, especially in QLD.
I think also people need to realise the definition of the business traveller has changed, forever. Occupations that were seen as blue collar (miners, electricians etc..) can now be flown in and out around the country for business and pull in over $100k easily. Are these people less able to conform to the rules of the QP? No. But I don't think you could argue being not from a old school 'business' type, their definition of fashion taste is not the same as yours.
Add to the fact that more and more corporations offer discount & before tax lounge access memberships for their employees (ie my QP membership), your true business traveller pool is being diluted again.
I know I've had some strange looks getting into QP & J class with my polo, shorts and shoes, but I couldn't give a rats, my money is the same as yours!