There was uproar last month as supermarket Aldi pulled Roald Dahl's Revolting Rhymes from its shelves, because of a misunderstanding of the writer's use of the word "slut".

Dahl was no angel, but 'slut' was not meant to offend

The beloved children's author didn't intend to offend. The word had an entirely different meaning back in his day, given to a woman with low standards of cleanliness.

Yet with so many "helicopter parents" buzzing around, ensuring everything is perfect for their little angels, it's no surprise one misguided mum or dad took offence.

Several of Dahl's books - noted for their naughty nature - have been banned in countries across the world, and he's not the only one: dozens of seemingly innocent kid's tales have been questioned on their content.

But the most controversial texts often turn out to be the most collectible, and some are now worth tremendous sums. So to mark Banned Book Week (September 21-27), here's 10 to discover.

10. Dr Seuss - Green Eggs and Ham

China was concerned that Seuss' rhymes could turn an entire generation into Marxist revolutionaries

"I'm as subversive as hell!" the writer once said.

Yet we don't think he was attempting to subvert with Green Eggs and Ham, in which the irritatingly persistent Sam-I-Am attempts to force-feed his friend the revolting titular dish.

However, the Chinese government managed to find a deeper context (one we certainly didn't pick up on as wide-eyed youngsters). The government banned the book in 1965 for its supposed "portrayal of early Marxism".

Even the most adept political thinkers among us might struggle to link the two, but even so, the ban was only lifted in 1991, when Seuss passed away.

Today, first edition copies of the book are worth upwards of $7,000 - find a copy of the book in Chinese and you'll be sitting on a fortune that will leave you scoffing at Marx's proletariat dreams.

Seuss' The Lorax was also banned in California for a while after claims that it would cast logging in a negative light to children...

9. Lewis Carroll - Alice in Wonderland

With the author a respected reverend, its unlikely the book was a slight against religion

We all know there are some hidden messages in Alice in Wonderland, particularly pertaining to drug use (we're looking at you, hookah-smoking caterpillar).

Yet China (again) took an entirely different view, excluding the book from library shelves due to its portrayal of animals as humans, which apparently suggests that animals are equal to our superior form.

New Hampshire also banned Lewis Carroll's surreal book as it supposedly "contains expletives, sexual content and derogatory characterizations of teachers and of religious ceremonies."

Given that Carroll's true name was Reverend Charles Lutwidge Dodgson, we find the latter charge hard to believe. 

Highly collectible today, a first edition copy of the book inscribed to Alice Liddel - the inspiration for the story - sold for $15,000 at auction recently, and that's far from the highest price seen for Carroll's work.

8. JK Rowling - Harry Potter series

Potter's adventures have been criticised for promoting witchcraft yet have also been described as an exploration of Christian themes

Yep, Rowling's beloved boy-wizard has been snubbed by religious types across the world, including Christians, Muslims and Mormons.

In fact, only Judaism (and Wicca, of course) have stood up for Potter and his pointy-hatted pals, with one rabbi describing the books as "a force for good".

No-one can argue with Potter's good intentions (come on, the kid saved the world from a serpentine Ralph Fiennes), but it appears to be the vaguely Satanic nature of magic that irks the praying public.

One parent said: "If they are going to pass out witchcraft certificates they should also promote the Bible and pass out certificates of righteousness." 

Get your hands on one of the 500 first edition, first printing copies of Harry Potter and the Philosopher's Stone and you'll be worshipping the pagan god of collectibles in no time - the record for a first edition at auction stands at £28,500 ($43,750).

7. EB White - Charlotte's Web

Muslims don't eat pork, but they do acknowledge the existence of pigs

Despite the threat of slaughter throughout, there are few books as charming as Charlotte's Web.

Set in the countryside, the books tells the story of a pig named Wilbur, who escapes the meat grinder thanks to the help of a spider named Charlotte.

Again, the anthropomorphic representation of animals irked some religious folks in America, but it was one UK teacher's decision to remove all copies of the book from the school's library that was really absurd.

In the well-intentioned but misguided thought that the main pig character might offend Muslim students, each copy was pulled from shelves.

A series of 42 original illustrations for the book sold for $780,000 at Heritage Auctions in 2010.

6. Bill Martin Jr - Brown Bear, Brown Bear, What do you see?

'Brown Bear, what do you see?' Hordes of angry Texans shouting about Marxism

We've seen some spectacular displays of idiocy so far in this list, but this one takes home top prize.

The Texas State Board of Education decided to ban "Ethical Marxism: The Categorical Imperative of Liberation" by Bill Martin, a philosopher and advocate of Marxism.

Given the US stance on all things of a communist nature, it wasn't surprising the decision was made. What was a bit of a shocker was that the Texans somehow got their wires crossed, and banned this adorable 1967 picture book by Bill Martin Jr (no relation).

Considering the contents is aimed at infants, to help them identify basic shapes and objects, it is hard to believe no one flagged up the mistake.

First editions are already rising to $100 - did the controversy inspire collectibility?

5. Shel Silverstein - The Giving Tree

The little boy later became the basis for the character of Christian Grey

Shel Silverstein has had some of his cartoons published in Playboy. Big deal, right?

For some people, the writer's previous employment was enough to question The Giving Tree's suitability for children, despite it being hailed by some churches as "a parable on the joys of giving".

Some even tried to claim that the bending tree was a "suggestive illustration".

However, some nitpicking psychologists still weren't content, analysing the book to find a much greater evil: the sadomasochistic relationship between the tree and the little boy.

Yes, really.

While the tree is all-giving and loves the boy without condition, the selfish little boy just takes, takes, takes. One shrink even described it as a "vicious, one-sided relationship".

When readers told the naysayers quite how ridiculous their ideas were, renewed cries that the book was sexist (for portraying all little boys as selfish) were heard. These cries fell on deaf ears, until one elementary school teacher banned the book simply for encouraging children to break dishes.

Mint condition copies of the 1964 first edi