A recent conversation with a student started with something very ordinary: school lunches.

She mentioned being responsible for school lunch hygiene, which led us to talk about an old English proverb: Cleanliness is next to godliness.

Godliness is an old-fashioned word meaning moral or spiritual goodness. The phrase was popularized in the 18th century by John Wesley, the founder of Methodism, who used it to express the idea that physical cleanliness was closely connected to spiritual and moral purity.

By Victorian times, this idea was deeply embedded in British culture. Physical cleanliness, tidy homes, and polished manners were increasingly associated not just with health and respectability, but with moral character.

That historical legacy helps explain why modern English still uses clean and dirty to talk about morality far more often than we might realize:

- a clean record: no history of wrongdoing
- dirty money: money obtained illegally or dishonestly
- dirty politics: dishonest or unfair behaviour

We subconsciously map these ideas together: clean suggests purity, honesty and respectability, while dirty suggests corruption, dishonesty or something morally questionable.

From Moral Codes to Movie Genres

Once these associations become part of a language, filmmakers can use them to create characters and stories.

Cinema often plays with the gap between how someone looks and who they really are. A character may appear clean and respectable but have a very dirty secret. Someone who looks rough and dangerous may actually be the most morally principled person in the story.

Different movie genres have been using this contrast for decades.

1. Classic Westerns: Clean Towns and Dirty Outlaws

Classic Westerns often use physical appearance to establish a clear boundary between order and disorder.

The respectable townspeople live by rules, while outlaws and gunslingers exist outside them. The sheriff arrives to clean up the town, while criminals may be described as dirty or rough.

But Westerns also love to turn these expectations upside down.

The hero may be dusty, unwashed and rough around the edges, yet have a stronger moral code than the neatly dressed mayor or businessman. Someone who initially appears to be an outsider can ultimately prove himself to be the person who restores order.

After making amends for his past, he may even be given the chance to wipe the slate clean and start again.

2. Gangster and Mob Films: The Polished Criminal

Gangster films take the contrast even further.

Figures such as the gangster Al Capone or Michael Corleone (The Godfather) are often impeccably dressed in expensive suits. They look like respectable businessmen or corporate executives, but their actions are anything but clean.

This contrast is reflected in the language of crime films:

- keep your hands clean: avoid direct involvement in something dishonest or illegal
- make a clean break: completely escape from a situation, relationship or past life
- dirty money: money obtained through illegal or dishonest activities

A gangster doesn't necessarily look dirty. In fact, the more polished he looks, the more powerful the contrast can become.

The suit is clean. The money isn't.

3. Thrillers and Noir: The Mask of Respectability

Thrillers and film noir often take this idea to its darkest extreme.

The most dangerous character may be the person who looks like a quiet neighbour, successful businessman or respectable member of the community. Behind that tidy appearance, however, there may be corruption, deception or violence.

The language of these stories often revolves around exposing what has been hidden:

- a dirty secret: an embarrassing, immoral or illegal truth that someone keeps hidden
- wash your dirty laundry in public: expose private or embarrassing problems in front of other people
- a dirty trick: a dishonest or unfair action designed to deceive or harm someone

The respectable appearance becomes a kind of mask. The story becomes interesting when that mask begins to slip.

Appearances and Reality

Whether it is a dusty cowboy who turns out to be a hero or a suave businessman running a criminal organization, these stories work because we enjoy discovering that our initial assumptions were wrong.

The character who looks clean may not be clean at all.

And the person who looks dirty may turn out to have the cleanest conscience.

The conversation that started with school lunch hygiene eventually brought us to one of the oldest ideas in storytelling:

Appearances can be deceptive.

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Learning Support: Vocabulary and Key Expressions

Cleanliness is next to godliness
Meaning: A traditional proverb suggesting that physical cleanliness is closely connected to spiritual and moral purity.

A clean record
Meaning: A history without criminal or other serious wrongdoing.
Example: He has a clean record and has never been arrested.

To clean up a town
Meaning: To reduce or remove crime, violence or corruption from a place.
Example: The new sheriff promised to clean up the town.

To wipe the slate clean
Meaning: To forget or forgive past mistakes and make a fresh start.
Example: They decided to wipe the slate clean and start their relationship again.

Rough around the edges
Meaning: Basic, unpolished or lacking refined manners, but not necessarily a bad person.
Example: He can be a little rough around the edges, but he's actually very kind.

To keep your hands clean
Meaning: To avoid direct involvement in something dishonest, illegal or unethical.
Example: He knew what was happening but kept his hands clean.

Dirty money
Meaning: Money obtained through illegal, fraudulent or dishonest activities.
Example: The police believe the company was being used to launder dirty money.

To make a clean break
Meaning: To completely separate yourself from a situation, relationship or past life.
Example: After leaving the company, she wanted to make a clean break with her old life.

A dirty secret
Meaning: An embarrassing, immoral or illegal truth that someone tries to keep hidden.
Example: Everyone thought he was respectable, but he had a dirty secret.

To wash your dirty laundry in public
Meaning: To discuss private, embarrassing or uncomfortable problems in front of other people.
Example: I don't want to wash our dirty laundry in public.

A dirty trick
Meaning: A dishonest, unfair or deceitful action intended to deceive or harm someone.
Example: That was a dirty trick, and I won't forget it.

Appearances can be deceptive
Meaning: What someone or something looks like may not reflect what they are really like.
Example: He looks intimidating, but appearances can be deceptive.