In which case - they could maybe wear disposable gloves - I would not want to frisk anyone without protection anyway - dirt is not always visible..
I myself had on clean jeans and T Shirt as well as my Hi vis (clean) and ID badge (displayed in the correct manner)- something which I am sure the Security guard in question would probably have noticed and been able to use his or her discretion about had I had been an 'apron' worker and had the temerity to mix with the public -
incidently; living in Bramhall and being one of the obviously more educated Security personnel; why not suggest to 'Management' that they allow staff access via the 'Fast Track' - I never see anyone go through it anyway