At my workplace, I have a monitor of reputed company with touch buttons with back-light which aren't visible unless the monitor is switched on. This includes the power button.
Occasionally, I spend more than half a minute trying to find the power button button to switch on the monitor by feeling around the right hand bottom corner.
My colleagues have 3 other models of monitors of the same company, but only one of them has buttons which are visible even when the monitor is switched off.
Is this just bad design or is it useful in some way?
More generally, can it be said that touch buttons should always have a static physical (non-electrical) symbol around them which makes them visible even when the device is switched off?