I've been suffering from this type of texture tearing for quite awhile. I am not even sure if it is a texture tearing.
The symptom is that the textures on the building (usually) starts waving and moving if looked at from a distance. If I get close to it, it looks perfectly fine.
I don't really know how to describe my situation, I will say the texture looks very "edgy", I guess.
Here are two example screenshots of my situation.
It gets kind of annoying whenever I am farming something, because the textures look like they are keep moving inside them and it just gets me.
PC Spec is i7-5500u / GTX 950M with latest graphics driver, 8 GB RAM.
Any kind of video settings didn't resolve my issue, reinstalling graphic drivers (up-to-date fyi), or anything.
Only happens in WOTLK wow client. I tried redownloading client too.
Edit :
Edited: December 29, 2015
Reason: forgot to add pictures.
Its the amount of Bits per pixel, this helps distinguish the color differences. The setting for you was probably 16. There are 3 different settings.
16 (high color), 24(deep color) and 32(true color).
I just realized that you'll have to use that every time you login. So to make this last forever, you'll need to open your config.wtf file and add the following lines:
SET gxDepthBits 24
SET gxColorBits 24
You can play around with 24/32. Just make sure deph and color bits are the same values.
lag/performance will depend on your graphics card