"Spot on - it's just ludicrous!" snaps Geoffrey Nunberg, a linguist at the University of California at Berkeley.
"You are just impersonating an Englishman when you say spot on. Will do - I hear that from Americans. That should be put into quarantine," he adds.
And don't get him started on the chattering classes - its overtones of a distinctly British class system make him quiver.
But not everyone shares his revulsion at the drip, drip, drip of Britishisms - to use an American term - crossing the Atlantic.
"I enjoy seeing them," says Ben Yagoda, professor of English at the University of Delaware, and author of the forthcoming book, How to Not Write Bad.
"It's like a birdwatcher. If I find an American saying one, it makes my day."
Last year Yagoda set up a blog dedicated to spotting the use of British terms in American English.
So far he has found more than 150 - from cheeky to chat-up via sell-by date and the long game - an expression which appears to date back to 1856, and comes not from golf or chess, but the card game whist. President Barack Obama has used it in at least one speech.
Yagoda notices changes in pronunciation too - for example his students sometimes use "that sort of London glottal stop", dropping the T in words like "important" or "Manhattan".
We are not seeing a radical change to the American language, says Jesse Sheidlower, American editor at large of the Oxford English Dictionary - rather a "very small, but noticeable" trend.
Bill Kretzschmar, professor of English at the University of Georgia, makes a similar point - that while the spike in use of some British terms may look dramatic, it is often because they are rising from a very low base. Most are used "very infrequently", he says.
And it is not so much the masses who use these terms, says Geoffrey Nunberg, as the educated elite. Journalists and other media types, like advertising agencies, are the worst offenders, in his view.
"The words trickle down rather than trickle up," he says.
"It sounds trendy - another borrowing we could use without - to use a British term. It just sounds kind of Transatlantic."
Some words, often the more formal ones, were once common on both sides of the Atlantic, but dropped out of American English usage while remaining popular in Britain, says Yagoda -amongst (instead of among), trousers(instead of pants), and fortnight (two weeks) are examples.
And some words which Brits regard as typically American - including "candy", "the fall", and "diaper" - were originally British, but dropped out of usage in Britain between about 1850 and the early 1900s, says Kory Stamper.
"America has always welcomed words from all over," she says.
"If it doesn't look conspicuously foreign, I don't think anyone questions - it's just English at that point."
The word gormless (the best American equivalent is probably "clueless") is on the rise in the US, for example, says Stamper, but no-one thinks of it as a British word. For some reason it sounds Southern to many American ears.
These days, the "balance of payments" language-wi
se is very much skewed the other way - with Americanisms used far more in Britain than the other way round, says Nunberg.
And though a few people do take umbrage at the use of British words in American English, they are in the minority, says Sheidlower.
"In the UK, the use of Americanisms is seen as a sign that culture is going to hell."
"But Americans think all British people are posh, so - aside from things that are fairly pretentious - no-one would mind.