I have just recently done a low-poly model of a car and I was painting it in Blender using the Vertex Paint mode. I had the faces of the body of the car selected and I chose the colour from the paint panel as you would. To confirm the colour I had chosen I clicked on the Set Vert Colour button. Then when I unselected the faces on the model the colour was not applied. Also when I to come out of vertex paint mode the colours that have applied themselves to the model seem to disappear. Should Blender do that? Thanks for your help much appreciated.
To see vertex colors in the 3D view, set the Draw Type to “textured”
To see vertex colors in the render, select either VCol Light or VCol Paint in the material.
BTW, I don’t think vertex colors work with GLSL yet.