Why would anyone VOLUNTEER for this?

"Revellers" swabbed for drug abuse
A device which can be used to detect traces of illegal drugs on people's hands has been used in Tayside for the first time.  Officers used the £25,000 Itemiser on revellers going into pubs and clubs in Arbroath on Friday and Saturday night. People are not legally required to provide a hand swab but many do so voluntarily.
Care for a quick wipe down, sir?  FUCK OFF! 

And I'm sorry but I don't believe anyone in Arbroath could, by any stretch of the imagination, be referred to as a 'reveller'.