The short answer is that solenoids always pull plungers in towards the center of the solenoid. For AC solenoids swapping wires shouldn't matter. DC solenoids have diodes installed so wires shouldn't be swapped.

The long answer is that the plunger doesn't care about the direction of the magnetic field. In fact, in AC solenoids the magnetic field, like the electric current, is changing directions many times each second. All the plunger cares about is the density of the magnetic field.

When current flows through the solenoid it creates a magnetic field that looks pretty much like the magnetic field around a bar magnet. (Remember bar magnets and iron filings in grade school?)
Electromagnet (resized).jpg
The curved field lines surrounding the coil represent the magnetic field. Think of it as a topographic map of the magnetic field. The closer the lines are together the more magnetic field there is. The field is most dense in the tube in the solenoid so that's where the plunger wants to go.

If the plunger were replaced by a magnet of the same shape then yes, the direction of the current and of the magnetic field could attract or repel the magnet. But since the plunger isn't magnetized all it cares about is the magnetic field density.

/Mark