Here is what the wave looks like with a dimmer at 50%:
You aren't going to smooth that out with a resistor. Only thing that can help is a capacitor and that is beyond a capacitor at that point. The green line is what a sine wave dimmer does to the wave. As you can see, no bumps which means it should dim evenly. That butchered wave is also what causes lamp sing, that buzzing you hear from lamps when they are between roughly 90% and 10%, the worst being around 50%.