I had a suspicion that this was the case:

Did it really need new toner—or was my printer lying to me? [...] This guy had also suspected that his Brother was lying to him, and he’d discovered a way to force it to fess up. Brother’s toner cartridges have a sensor built into them; OppressedPrinterUser found that covering the sensor with a small piece of dark electrical tape tricked the printer into thinking he’d installed a new cartridge. I followed his instructions, and my printer began to work. At least eight months have passed. I’ve printed hundreds of pages since, and the text still hasn’t begun to fade.

It should really go without saying, but when the people responsible for making the system that tells you when you have to replace supplies and the people selling the actual supplies are one and the same you should double check that whatever level indicator it is is telling the truth.

Oral-B electric toothbrush heads are supposed to be replaced when the blue colouring of the bristles fades to white on half the length of the bristles. Turns out, when you look at them new and fresh out of the pack they already have a slight fading down to half. If you follow their advice you’ll spend a small fortune in toothbrush heads.

Same thing with Gillette razor blades. You’re meant to replace the blade when the indicator strip fades. That, incidentally, happens suspiciously quickly too, and the blades are good for quite a few shaves after. I’ve stopped using their crappy products all together and have opted for a tub of Geo.F. Trumper, a badger shaving brush and a good old fashioned single blade safety razor. Cheaper in the long run and a much better shave with the added benefit of knowing exactly when I’m out of supplies: the tub is empty. As for the blade, the precision you have to use with a safety razor makes it much easier to tell when the blade isn’t doing its job anymore.

Not really related, but all this talk of Gillette reminds me of an article from The Onion from 2004. It was meant as a joke back then, and Gillette had sworn that 5 blades was overkill – there was no benefit. That was in response to the Wilkinson 5-blade razor though, and look where Gillette is now. No benefit indeed!