Muggs is right. I'm not as low as some but my RDA builds run between 0.2 - 0.5.
As you can imagine juice vaporizing at 30+ watts is pretty warm and you don't want it spitting at you.
When I drip through the top some juice sits on the coil meaning when I fire it's going to spit off. So right after dripping I blow real quick before inhaling.
The same thing happens if I haven't hit for a period of time. So for the first hit everybody figures out to do that.
If they do it after the first hit they probably over dripped and it's just bubbling / spitting juice at them. So they are blowing the excess juice off.