Painting on mesh doesn't work I can't paint on mesh, but can in uv/image editor. I believe I saw solution long time ago and cant find it anymore. Also everything work with new blend file. I probably pressed something and can figure it out what. Its not face masking.
So as @moonboots pointed, the problem was that in "Texture paint mode" ToolShelf>Slots>Mask checkbox was enabled. It must be unchecked in order to draw on mesh itself.