How to verify whether an electrical appliance is properly grounded?
If you’re at all uncertain, get a professional to check for you, it’s as simple as that.  If you are a professional then you’ll measure the resistance between the device in question and a known-good earthing point.  Electricians probably have a dedicated instrument for doing this but the way I’ve done it in the lab is to pass a known current (e.g. 1A) from the device to the ground point and measure the voltage drop, 1V corresponds to 1 ohm of resistance.  For a domestic appliance 5ohms appears to be a rule of thumb, but check the regulations for your country/jurisdiction.
If an appliance that draws 10A were to pass all its load current to earth then it could present 50V if it were touched, this is unlikely to result in electrocution.