Do household AC motors (mixer, vacuum cleaner, etc) work as electricity generators if used in reverse?

Only if the motor is a permanent magnet type motor. Most motors are electromagnetic, having electromagnets that operate only when A/C current flows through the coils of the field. If no current flows through the motor's field windings, then there is no magnetic field to pass, or rotate the stator through, so it will not create energy. When current flows through the fields, the motor is only a motor. On permanent magnet motors the magnets do not need to have current to work, so when the stator passes through the magnetic field, such as in a wind turbine, it creates energy.  more