There's a LOT of shoplifting. If a person did it a few times, their picture was put up behind the customer service desk where the tannoy is and you weren't allowed to serve them, as they'd try and exchange items that they stole.
Funnily enough, we never had any detectors, but the security guards were really good.
You'd get people trying to return things such as underwear or swimsuits without the sticky label (we'd never accept them back) or skid marks/foundation marks etc. Yuck 