Starting from ArcMap 10.1.1, enabling the customize setting "Use large toolbars" has a nasty looking side effect. Dropdown toolbars have a generic icon on the background of it. It looks hideous, Not to mention the icons that come with ArcMap are all in 16x16 pixel icons. When the toolbar is bigger, it should have 32x32 pixel icons, but now they are just sized with the same 16x16 pixels.
My idea: Fix the toolbars for use larger icons setting.