All UI elements in apps ugly and grey (14.04)

Solution 1:

This right here is an easy fix. All you have to do is go to the software center and install Ubuntu tweak.

1. Open that up and go to "Tweaks"
2. Go to "Theme"
3. In there, change the Gtk theme to whatever you like.

That should fix it up no problem

Solution 2:

There might be many reasons for this problem, but it can typically be fixed by re-configuring your themes. You can start by tweaking the theme in unity-control-center and making sure it is set to Ambience. If it is, try switching the theme to a different one and back. You can also try reinstalling the themes as suggested in this answer: https://askubuntu.com/a/141375/341801 for 12.04.