I've noticed some objects in Frostfang Sea on live appear to have adjusted vertical headings so at some point SOE has added this functionality. In other words besides just being able to turn objects/spawns horizontally there is the ability to make them face upwards or downwards more as well.
List of spawns I've noticed this on for a reference:
Spawn ID 4701580 (model id 13279)
Spawn ID 4701728 (model id 2998)
Spawn ID 4701747 (model id 6250)
Spawn ID 4701636 (model id 8194)