Almost 10 per cent of 3,500 of 36,000 dining establishments in New South Wales failed the state's hygiene test. Among their violations are preparation of food in dirty kitchens and failure to control the spread of bugs.

Topping the list of the restaurants on the NSW Food Authority's Name and Shame register is Domino's Pizza with 31 of its branches given 50 penalty notices.

On second place is KFC with 24 branches and a total of 40 fines.

The closed Hong Hai Noodle Bar in the Central Business District is considered the worst re-offender based on its 21 penalty notices worth $8,580, including five fines slapped in 2012.

In the July 2012 list of the Food Authority, Domino's Pizza at Cambridge Park was added to the roster, plus the Pizza Hut outlet in Orange, McDonald's at Yass, Sumo Salad at Macquarie Park and Coles Express at Willoughby, although Coles was placed because of selling expired products.

Of the 8,042 penalty notices issued by the Food Authority in the last five years, over 1,000 were due to cockroach infestation, rodent activity and insect droppings in their kitchens. But more than half of the offences were due to areas considered unsanitary for food preparation, dirty equipment and lack of easy access to hand-washing facilities.

If the types of violations were known to consumers, mostly likely they would avoid these establishments. Among the worst violations were the Jemes Fish Market in Ashfield caught keeping live crabs in a toilet cubicle, the Choy Restaurant in Randwick was discovered to have a dead rat in its storage area and a bakery in Marrickville cooling their baked products outside in trolleys in a multi-business industrial car park accessible to anyone.

Because of the Name and Shame register, NSW Primary Industries Minister Katrina Hodgkinson noted that the number of dining establishments on its dirty list has done down to 785 in 2011/12 with 1,337 penalty notices from 1,309 restaurants in 2009/10 with 2,329 penalties.