In the renderer.info stats, the scene background is additive to memory.textures and programs, but not to memory.geometry.
And even after this bug is corrected, this still can be confusing when trying to understand or keep track of gpu memory.
I'm thinking it would be better if we listed the background separately. Something like this:
renderer.info.background
geometries: 1 // currently this displays as 0
textures: 1
programs: [WebGLProgram]
renderer.info.gpu
geometries: 3
textures: 2
programs: [WebGLProgram, WebGLProgram...]