All most people want to do at a Self-service Automated Machine (SAM) is to buy a postage label, get their letter in the mail and return to their busy lives.
But logistics project leader Poh Kian Hwee, 43, spends a few hours a week at these machines, his eyes fixated on the labels popping out one by one, looking for the elusive printing error that occasionally rewards him.
A breakthrough came in 2009 when, at the SAM kiosk at Great World City, he noticed that the labels with an illustration of the Singapore skyline were missing the words "Garden City" that were supposed to be there.
Excited, he returned to the machine twice that day, spending an hour each time using his Nets card to buy the labels, which were misprinted before they were loaded into the SAM kiosks.
He bought 1,000 copies, and as the machine dispensed a maximum of 40 labels at a time, he had to key in his PIN at least 25 times.
Eight thousand of these misprints are thought to have been dispensed - 4,000 each at the SAM kiosks at Great World City and the Singapore General Hospital - but Mr Poh reckons that his were the only survivors, as "99.99 per cent" of used labels end up in the trash.
The error even made it into the catalogue of Singapore stamps published by local stamp dealership CS Philatelic Agency, which valued it at $20 apiece.
This makes his entire label collection worth about $20,000, as the rest are mostly worth their face value.
However, Mr Poh was quick to point out that the misprints may have a high catalogue value but there is no market for them.
More important to him is the overall collection he has amassed since SAM kiosks were launched in 1997.
He has been at it long enough to see improvements in paper and print quality through multiple generations of SAM kiosks.
The more recent labels are nicer, having more subtle gradients of colour, said Mr Poh.
An exhibition of his collection at the Tri-Nation Stamp Exhibition in Chiang Mai, Thailand, in 2011 bagged him a silver medal.
He has even drafted a manuscript of a book about SAM labels, which runs into more than 100 pages.
He said, referring to himself: "You find yourself becoming very familiar with how the machine works and how it's printed - it gets fascinating.
"You're a pioneer in this area and you define the boundaries - it's lost if you don't write it up."