Actress Hailee Steinfeld pairs a navy-and-white dress with white strapped sandals at an event in Los Angeles in 2013.
If the oil is on the inside parts of the spark plug like the bottom insulator, that's a bigger issue, you have either leaking valve seals or very leaky piston rings. If your car blows a puff of blue smoke on startup, you probably ave leaky valve seals. If it blows blue smoke all the time, leaky piston rings.
The excessive vibrations can cause engine mounting eventually to fail. Extreme cases of oil fouling can cause hard starting, engine stalling and ignition coil failure. The ignition coil is connected to spark plugs by high-tension wires and sends surges of electricity to fire the plugs. Oil-fouled plugs send the surges back to the ignition coil instead of its normal path.