Mistakes and odd writings on old monetary notes can make them much more valuable.
Why funny money is the very best kind
One Arabic letter missing, and a five-riyal Saudi note suddenly becomes a "khassa", or lettuce, instead of a "khamssa."
A Dh100 note is almost glowing because of its fluorescent pink colour, instead of its customary subtle pink.
Burn marks on a 1917 Indian one-rupee note forever capture the moment when one of its owners tried to iron it to keep it looking new.
These errors and unsuccessful innovations on banknotes can make them the rarest and most expensive to own, according to the money and coin collector Ahmed Al Hasawi.
"Look here: you see the corner?" he says, pointing to the bottom right corner of a Dh500 bill.
To the average eye, the corner looks just fine. But to Mr Al Hasawi's experienced eyes, there is a mistake.
"It is small, but you can see it clearly how it wasn't properly printed and is not perfectly aligned," the 31-year-old Emirati from Umm Al Qaiwain says.
Mr Al Hasawi, who has been collecting for more than a decade, says that unless someone takes the time to carefully examine what they have in their wallet, it is difficult to spot oddities in money.
"Many of the currencies and coins that looked imperfect or strange, people threw away or sometimes even melted down to be able to sell as solid metal," he said. "Now, they are treasures. The stranger and funnier the mistake, the more it is wanted."
Islamic-era coins are particularly expensive and rare, selling for millions of dirhams. Each coin is different, depending on who minted it and when.
Mr Al Hasawi is particular about his collection, which is carefully put away in special albums made for paper currency, and plastic pouches for coins.
"Hold it like this," he says, grasping the edges of a rare golden coin between his fingers.
He doesn't allow anyone to touch the centre, which has two beautifully shaped gazelles running on one of its sides. The other side is plain, as the coin was not meant for circulation.
"It was one of the experimental designs they were playing around with before they launched the national dirham coins and currency," he says.
The display coins that never made the cut for widespread circulation are among the most sought-after local collectables.
Like Mr Al Hasawi, Marwan Al Marzooqi, 35, of Sharjah, reluctantly shares his rare and strange treasures.
"Recognise him?" Mr Al Marzooqi says, pointing to a coin from Ajman minted in 1970, with a distinct head figure of the Soviet revolutionary leader Vladimir Lenin.
In the early days of the UAE, each emirate would commission the minting of coins that took its fancy.
"Most have nothing to do with the UAE, but are quite beautiful to collect," Mr Al Marzooqi said.
Both Mr Al Marzooqi and Mr Al Hasawi started collecting UAE currency, then expanded and started bidding for regional currencies.
"It opened a whole new world for us, and we don't look at money the same way anymore," Mr Al Marzooqi said."Actually, I think we look at it more closely than anyone else."
Regional collectables tell interesting stories.
"Imagine how many hands touched this money before we finally got it?" Mr Al Marzooqi asked.
But among the favourites, and harder to get, are handwritten cheques from the region's long-gone luminaries and rulers. Some had spelling mistakes, some had forgery attempts where someone played with the figures.
Within their collections, for example, are two cheques issued by The Arabian National Bank of Hijaz, from the 1920s, before the foundation of Saudi Arabia.
The cheques provide insight into the social customs of the time.
"Here, it is paid out to someone given the title al Khawaja, meaning foreigner, so probably he wasn't from the area," Mr Al Hasawi said, reading from one of the cheques. "In the other, it is al Moalem, which could mean this person was actually a teacher or someone revered and educated and so given this title of respect."
Both are signed by an Egyptian prince named Habeen Lutf Allah Basha.
"It is too bad they don't make many mistakes these days," Mr Al Hasawi said. "If we notice anything, it is more likely the note is counterfeit to begin with."