I installed kubuntu-desktop and every thing was fine. Then later when I actually logged in to Kde, I decided that I still like Unity better so I ran sudo apt-get purge kubuntu-desktop && sudo apt-get autoremove. After that bits and pieces of my Ubuntu/Unity have been Kde styled. All browsers have Kde icons and some applications show 'About Kde' in their menus, all text fields have that 'bluesh glow' around them, etc.
What is still left of Kubuntu?
Note: I saw this question and this question, but both where outdated and didn't work.
Remove from your $HOME directory any file that is of the form
.gtkrcAfter removing such files, go back into your Appearance settings and change your theme to Ambiance or Radiance, apply, then move onto your preferred theme.Please check the setting of Ubuntu in System Setting.
TO ensure you run the correct version, you should + Install unity GUi + Change setting + Reset computer again to change setting I guess you change on an account but check on other account
I tried this under ubuntu 14.04. It removes all remaining traces of kde and reinstalls ubuntu-desktop.