They can be dangerous !!!!
For the record all appliances should be plugged directly into their own receptacle, never using an extension cord or plugged into a power strip!
If, however, you happen to be working on anything (in our case an appliance) plugged into a power strip DO NOT flip the little switch on the side and trust that the power has been disconnected to whatever you have plugged in to the strip! Regardless if the lights go out on the appliance!