All Wood Blocks (Oak, Spruce, Birch, Jungle) and Quartz Pillars have inconsistent side textures when placed on their sides, when they are placed vertically their side textures ARE consistent.

Edit- (May 12, 2013), Also exists with Hay Blocks in 13w19a.

This Bug/Glitch was found in Minecraft 1.5.1 and the most recent snapshot, 13w19a.

When I placed one of the blocks on it's side I expected the side texture to be the same around the block. I expected this because the textures on the side of the block when positioned normally (up and down) ARE the same all the way around the block.

When I placed any of the blocks on their side, the texture was not the same all the way around the block.

Links to images:
http://imgur.com/2jQkyE1,SC3sD1j,27Gkqjs,Y1td2EO,BiqoWmP,K8srBAG

http://imgur.com/xV8zX6P