Maybe zoomkat will tell you which servos he has that don't twitch on power application.
Some of the discription is strange in that no matter where the servo is physically positioned, it always moves 30 deg. This is strange in that the servo should move to some default control signal position when attached.
Re the 1st half, I have some GWS servos that jump literally 30-deg when power is applied, and NO pulses are being sent. If I re-apply power several times, I can get the servo to jump a full 180 deg around the clock,until it gets over to its mechanical stops.