The Armor Stands in the following picture have been summoned using the following commands:
/summon ArmorStand ~ ~ ~

{Rotation:[0f,0f]}

/summon ArmorStand ~ ~ ~

{Rotation:[90f,0f]}

/summon ArmorStand ~ ~ ~

{Rotation:[180f,0f]}

/summon ArmorStand ~ ~ ~

{Rotation:[270f,0f]}

http://gyazo.com/fdc5c70f708fa65255946b154933ae0b

As this screenshot reveals, Armor Stands only show up correct orientation lines when they have a "negative rotation".
A negative orientation is a Y-Axis Rotation of 0<x<-180.

All Armor Stands with a "positive rotation" show up weird lines that go more or less into positve Z direction.
This includes the Armor Stands summoned with the first two commands.

Also, you should note that orientation lines all point straight into positive Z before you move the ArmorStands using teleportation.
Other forms of motion such as falling do not update the orientation lines.

However, as the following video reveals, you can still "fix" the broken orientation lines by rotating the Armor Stand with a teleportation command.

http://i.gyazo.com/371c178b61a2b331caf8f33c8439f334.mp4

Summoning an Armor Stand and using the command "/tp @e[type=ArmorStand] x y z ~ ~" will not fix the orientation lines though.