Are you holding it perpendicular to your jaw? at an angle? 180, 90, 45 degrees? I have to say - I've been experimenting with all of the above, and haven't noticed a difference in performance. My vapor quality/consistency appears to be completely dependent on how often I top-off my cartridge with fresh
juice. I'm struggling to find any reaction from the angle in which I'm holding the PV to my mouth when I draw.
In general, the angle you hold the PV when you draw doesn't matter too much.
What CAN matter, though, is the angle you keep it when not in use.
If you keep it battery side down
juice will flow to the wick better.
But if your juice is too thin for your wicking material this can also lead to flooding.
If you keep it cartridge side down juice will have to fight gravity while wicking.
If your juice is too thick for your wicking material this can lead to poor wicking.
I try to keep mine cartridge side down when mostly full.
I try to keep it battery side down when mostly empty.
I prefer to keep it on it's side the rest of the time.
But in my opinion the best thing is too have good wicking material that is right for your juice, such that you can always keep it on it's side or battery side down without having to worry about any flooding.