Chefs and restaurant owners are already dealing with customers' out-of-focus shots of their masterpieces on Instagram, and mobs of bloggers tweeting and using flash photography in their dining rooms. But in the modern world, where everyone’s a critic with a smartphone, it’s customer review sites that they really find hard to swallow.

Restaurant review sites -- the new Yellow Pages and one-stop-shop for addresses, contact details and independent critiques -- have the hospitality industry on its knees.