Anyone who has spent time in Spain — and especially in one of the country's Catalan-speaking regions — in the run-up to Christmas will have seen the extravagant nativity scenes in the country's shops, homes and churches.

But look more closely, and you might find a surprise.

Among the figurines of the Infant Jesus, his parents, kings, and the camels and farm animals, Spanish Christmas cribs often contain a more unusual resident: the caganer, or crapper.

These characters are usually tucked away in the corner of the crib with their pants around their ankles — and defecating. 

Traditionally the caganer is a peasant from one of Spain's Catalan-speaking areas in a red 'barretina' cap. He is also often shown smoking a pipe. 

But Spain now has a booming trade in celebrity caganers with everyone from football star Leo Messi to US president Barack Obama coming in for the crapper treatment.

Click here to see The Local's gallery of celebrity crappers.

This year, for example, the number one seller on caganer.com is Pope Francis with statues of the pontiff doing his business going for a cool €16 ($22).

In second place, however, are statues of the Virgin of Montserrat, or La Moreneta.

La Moreneta — it means 'dark-skinned one' — is one of Europe's so-called black virgins and a highly venerated image in Spain.

With her home in the hills about Barcelona, and she is also the patron saint of Catalonia.

And this is where the problems have started.

The Bishop's Conference of Tarragona recently came out to say it "laments profoundly the use of the Virgin of Montserrat  as a grotesque figure in nativity scenes".

"The lack of respect towards such a highly esteemed religious figure is unjustifiable and offends the sensibility of Christians and all people with a religious sensibility and education," said the conference on its website.

The prior at the Santa María de Montserrat Monastery where the Virgin is housed told Spain's online Huffington Post newspaper the image was in "poor taste".

It was a sign of "decadence", Ignasi Fossas told the paper.

But crib-maker Marc Alòs at caganer.com rejected the criticisms. 

"As a crib figure, it's very well done," he told Catalonia's La Vanguardia newspaper. "From the front we can see her seated as she usually appears on the throne".

The new celebrity Caganers only date back two decades but the tradition may date back as far as the 16th or 17th centuries, according to the Friends of the Caganers website.

While they are considered a Catalan tradition, they can also be found in other parts of Spain, as well as in Portugal and Naples. 

"The placement of this uninhibited and controversial figure in the crèche is a counterpoint which adds a human side to the representation of the mystery of Christmas," the group says on its site.

"This down-to-earth symbol makes for a marvelous synthesis which harmonizes its transcendent and supernatural message with material reality and the biological condition of our organism." 

Click here to see more celebrity crappers.