Police in Taichung busted a counterfeit luxury watch seller who hid his stock in an emptied rooftop water tank — bad news for bargain hunters trusting cheap "brand name" deals on Facebook.

• Police spotted a Facebook seller offering IWC, Rolex, Audemars Piguet and Chanel watches for a few thousand Taiwan dollars, with one IWC listed at just NT$2,600.
• Test purchases confirmed the watches were fakes, leading to a court-approved search of the seller's Taipei home.
• The first search turned up only empty watch boxes and packaging, far short of what his online posts advertised.
• He eventually admitted draining the rooftop water tank and stashing the watches and computer gear inside to dodge inspection.
• More than 100 fake watches were seized, worth over NT$90 million at genuine retail prices; the case has been charged under Taiwan's trademark law.

Outlook: Police are warning shoppers that prices far below market value are the clearest sign of a counterfeit, and similar online sellers are likely to face the same scrutiny.