Why don't ailerons affect pitch? Why don't ailerons affect pitch, or do they?

I'm told spoilers can affect pitch if not placed in the right spot.

On a classic standard wing configuration, why don't ailerons affect pitch as they are at the trailing edge 
and would create a moment around the spar which I'm told it usually located at 25% chord
in ultralights.
Two reasons:  


Because they don't have a very long moment arm.
Because their movement works in opposite directions to each other, any pitching moment one side might cause is cancelled out by a pitching moment going the other way from the aileron on the other wing.