That all depends on what sort of heat source you are using.

Bic style lighter will give you flint dust and soot from the unburned butane
Elec lighters are a better choice as you get no flint dust, but the flame is still not hot enough to completely burn all of the butane.

Torches/micro torch is my preferred method when I am using my VG (and necessary when I am using my SV)

Plus I like the much quicker heat up time.