WattmeterLet's take a look on pretty old (but still working!) ink printer. I have HP Deskjet 845c at home, not using color since a long time, but refilling black ink is very easy. And it's nice to have printer at home. But how much energy does it use?
Power supply alone (no printer attached) uses 2.1W. After connecting the printer to power supply, it starts to use 3.1W. After powering on the printer (standby mode) power use... drops. To 3.0W, but it's lower than with "off" printer, despite LED is on!
It's clear, that if someone wants to save energy, there's no point to turn the printer off. Much better is disconnecting power suply, but this usually requires more work.