My Brother laser printer gave me the "Low Toner" warning over a year ago and refused to print. I put a piece of tape over the sensor window on the cartridge and I've probably spit out 1000+ pages since then. Sneaky bastards.

So, what exactly will happen when it *really does* need to be replaced? I've been waiting for/expecting something to happen for a really long time now....but something hasn't.

Your printouts will look like ****.

Wow really? There are printers out there that just REFUSE to print when that sensor is tripped?

See also: http://www.slate.com/articles/technology/technology/2008/08/take_that_stupid_printer.html
In there it said he was able to get 1800+ copies out after covering the sensor on the toner cart with electrical tape.

If I remember right, as you run out of toner, the prints become less and less visible until it just runs white paper through.

A while back there was an article in maybe PC Magazine that exposed a few of these printer companies that block printing when the cartridge gets to about 25%, when as you've seen for yourself it is fully capable of still printing just fine.

This. My printer, and every printer I've used/owned, have printed even after running completely out. This is odd news to me. =/

Newer printers are built like this, since our printer was free with a laptop I'm going ahead and guessing the revenue is made from ink now, not the printers.

revenue has always been from ink/toner.

Yeah, that's not new. I know someone that routinely buys new printers instead of new ink because it's cheaper (deals, coupons, etc) and then sells off the "old" printers.

Frankly, 95% of my printing is off a cheapo $80 laserjet I got off Newegg last year. It's still running on the toner that it came with, which was supposedly a half-filled cartridge. It's on 400 pages now, and still rockin'.

Toner sensor BS aside this printer was one of the best purchases I've made from a cost standpoint....I usually only print black and white and the toner seems to last forever. I was buying new black inks every month or two. Laser printer paid for probably 3 or 4 times already.

Toner tends to give you thousands of prints as opposed to the hundreds that ink cartridges give you. I have a color laserjet, and despite it costing ~$200 to replace all of the toner at once, I rarely ever need to replace more than one cartridge at a time and they last forever.