Tony Astle doesn't care to read diners' opinions of his Parnell restaurant, the venerable Antoine's. But he has scouts who do it for him.

While he would rather ignore the critics - professional or otherwise - Astle knows he can't afford to. Reputation is everything in the restaurant game.

"Usually those who have a gripe are people who don't like you," he says.

"We've been here so long [since 1973] that a bad review doesn't matter - people know our reputation and I have a very regular and secure clientele.

"But for a newish business, it can be all about competition, and rival restaurants will post bad reviews against them. They do it, there's no doubt about it, I've heard of it happening often.

"I couldn't be bothered with it personally. We might as well all hang up our spoons if that's what you have to do."

Astle says he can spot a "professional" grizzler from 10 paces. "You can recognise the troublemakers; they don't even know which cutlery to use," the chef says. "I must admit I have a lot of scouts who'll ring and say 'go online and look at such and such', and I can point the finger at the exact night that it would have happened."

Every now and again, diners threaten a negative review. He tends to ignore them. "I guess I'm a little bit rude when it comes to that sort of thing. There are professional complainers who don't have the guts to tell you to your face, but they'll ring up four hours later and say they have food poisoning. So you ask, 'What do you want me to do?'

"Then they ask for a voucher to come back again. If I got food poisoning from a restaurant, the last thing I'd want to do is go back there. They aren't very bright."

Overseas, guests are known for paying their compliments to the chef, and then posting them online, which Astle appreciates, but never invites. Sometimes, when Antoine's receives an adverse critique, flowers arrive from loyal customers.

"The other good thing about negative reviews is that they make you look at your business. Maybe their gripe was a true one. It makes you keep your eye on things, in case you could be getting complacent.

"More than likely, though, it's someone who has something against you, because you get a bad one and three good ones in the same week. You can tell by the way they write that it's vindictive. And when they can't spell, it's even more obvious."