"A useless piece of garbage who wouldn't know chemistry if it ran him over..."
"She spends all our lessons on her mobile texting her boyfriend..."
"I didn't like her as a teacher... she had a weird smell of vodka to her." (Anonymous posts on ratemyteachers.co.uk)
Teachers have always had to put up with personal jibes from kids.
Until very recently, however, malicious gossip and snide remarks have mostly been confined to the corridors or lunch queues.
But now with the explosion of websites like ratemyteachers.co.uk and bebo.com, teachers are suddenly finding themselves mocked in cyberspace, resulting in plunging morale and even threats to quit the profession.
Kathy Wallis, a senior teacher from Cornwall, says she recently had to talk a young colleague out of resigning over comments posted by her pupils on Rate My Teachers, a US-run site which allows kids anonymously to "grade", as well as criticise, their teachers.
"The teacher in question burst into tears and said 'Well if that's what they think of me I might as well give up teaching now'," she recalls.
"[Her students] had said that her preparation was dreadful, she had no classroom control and they made other unfounded malicious comments.
"Basically they just pulled her apart. It took two days for me to talk her out of resigning."
Ms Wallis claims that the site is seriously damaging trust between students and teaching staff.
"When you're facing a class five times a day, with 30 children at a time, and you don't know who has actually written these things, you become far more guarded in everything you do.
"And the bottom line is you lose all trust in the students you've got sitting in front of you."
Rate My Teachers, which was founded in the US five years ago, is growing in popularity in the UK.
The UK version of the site now features 454,000 ratings for 95,000 teachers at over 5,600 schools.
Speaking from New York, founder and manager, Michael Hussey, says he is surprised by some of the negative personal comments the Five Live Report discovered on his site.
"I'm not sure where you dug those up from... but most of those comments, as harsh as some of them are, are a single student's opinion."
He adds that there is a simple mechanism in place via which teachers - or indeed any registered user - can remove postings they find offensive.
However, Ms Wallis recounts that attempts to remove a posting about a colleague, who appeared on the site and then died shortly afterwards, have so far failed.
Moreover, she says it took nearly three weeks to remove a malicious allegation against a colleague, which was posted on Rate My Teachers, even after he was cleared by an investigation by the school's governing body.
Hussey responds by insisting that "any baseless accusation that is not in the realm of opinion... will be removed" and denies that Rate My Teachers is open to abuse.
"We've been doing this [site] for over five years and, yes, we've received a number of complaints over the years.
"But without question, we simply remove anything like that."
But while teachers may take issue with Rate My Teachers, such sites are apparently popular with their target market - school children.
"I know one teacher who I think is really rude," says a 15-year-old boy at Haydon School in Pinner, north west London.
"But there's no-one who can tell him that so, in a way, if they look at the site, it's good because they can change their attitude."
One of his classmates adds: "I rated my worst teachers. I said they were rubbish and didn't teach me anything."
Does she have any sympathy for those facing criticism on the site?
"No," she replies.
"Because I don't like them, they're just teachers."
Five Live Report: Bullied Teachers was broadcast on Sunday, 12 November, on BBC Radio Five and is also available on the Five Live Report website.
The charity Teacher Support Network and teachers' union the Association of Teachers and Lecturers (ATL) are running a survey into teachers' experiences of cyber-bullying, accessible via the website, above right.