The old expression may say "the customer is always right" but the sentiment is apparently not be shared by every shop assistant.

Britain's biggest retailer has been embarrassed by the revelation that dozens of its employees posted abusive comments about customers on a Facebook group entitled "Tesco employees could rule the world".

The group, which has now been taken down, had over 2,000 members confiding their true feelings for the shop's customers, who were described as smelly, stupid, rude and moronic.

One wrote: "I wish these f******s would just stay at home and shop online! That way none of us would have to deal with 'em!"

Another said that when asked for the location of a particular product, his instinct was to say: "Give me your damn [sic] shopping list you senile old cow, and I'll do your shopping for you. Just leave me alone."

Tesco has promised to take "appropriate action if necessary", and employees who posted comments could be investigated. Should they be? And are customers always in the right?

Digital Spy, a media, entertainment and news site, has several popular threads in its forums on retail workers annoyed by customers and another titled "what little tricks do you play on customers?"

In response to the Tesco episode, poster Pensioners Rule says: "In my opinion they are entitled to have a rant as a small minority of the British public do have the ability to be moronic, why shouldn't they be able to vent?"

Do you agree? Have you had to cope with annoying customers, or been on the receiving end of rude service?

I had a school job in a gift shop, and can certainly sympathise with retail employees, having had my own few run-ins with difficult customers.

But perhaps making your feelings known on such a public forum isn't the wisest idea.

Past examples suggest that venting opinions does not always end up well for the employee, as staff from Virgin Atlantic can tell you.

Last year 13 workers were sacked after posting comments on a similar group calling customers "chavs" and questioning the airline's safety standards.

So how should retail staff deal with difficult customers? Insults might not be the best way, but do you have any suggestions? Are there lessons both parties can learn to make the shopping experience a more harmonious one?