[skwasjer]

You can tone down the diffuse color for untextured view (in options dialog). When diffuse texture is off, it uses a simple single colored texture in it's place based on this color setting. It was full white in the initial model viewer release (which used a simpler shader), but I have left it unchanged...

Note that the material diffuse color is also blended with this global diffuse color, when the diffuse texture is off.