Many appliances continue to consume a small amount of electricity when plugged in but not turned off at the wall switch, due to standby power or trickle charge.
If you don't turn off an appliance at the wall switch when it's not being used, it will still consume electricity.

FactVerify
Source: factverify.com
Key Evidence
ScienceABC explains chargers and other devices draw small amounts of power even when turned off.
scienceabc.comscienceabc.comIf An Appliance is Plugged Into the Wall Socket, But Turned Off, Is It Using...
Consumer group Choice found that inefficient appliances left plugged in can cost over $100 per year.
abc.net.auabc.net.auShould I switch off power at the wall? Here's what you need to know for your...
Multiple energy advice sources confirm that turning off at the wall or unplugging is necessary to stop all electricity use.
greenyplace.comgreenyplace.comDo appliances use electricity when plugged in but switched off?
inspirecleanenergy.cominspirecleanenergy.comDoes Unplugging Appliances Save Electricity?
What the Evidence Shows
The claim that appliances still consume electricity if not turned off at the wall switch when not in use is supported by multiple sources. The key component of the claim is that simply switching off the appliance's own power button does not necessarily stop all electrical consumption; the appliance remains plugged into a live socket and can draw standby power. This standby power, also known as vampire or phantom load, is used by many modern devices to maintain functions such as clocks, remote control sensors, or network connectivity.
For example, chargers can draw around 0. 25 watts even when no device is attached, and other appliances may consume more depending on their design. Consumer group research and energy experts confirm that this standby consumption can add up over time, potentially costing consumers over $100 annually if many inefficient devices are left plugged in without being switched off at the wall.
The only way to ensure zero power consumption is to turn off the appliance at the wall switch or unplug it entirely. Some nuances include that the amount of power consumed varies widely by appliance type and model, and for some devices, the consumption when off but plugged in is negligible.
However, the general principle that leaving appliances plugged in without turning off at the wall leads to some electricity use is well established. Counterarguments noting that some modern appliances use very little power do not negate the overall truth of the claim but highlight variability in impact.
Therefore, the claim is accurate in its core factual assertion.