considering how many outlets are on a car wiring harness.
The answer is no! A bulb is needed to complete the circuit similar to a switch being turned off. The voltage is present but can go nowhere! However if something conductive to electricity falls into the empty socket (like a bare wire or other metal) then an electrical short would occur causing stray voltage and a tripped fuse!
Depends on your definition of stray voltage. When the light, if inserted. would be lit there will be 12 volts available at the socket. Just as there is 120 V AC at every plug in your house with nothing plugged in.
