I've tried this method using the smallest possible tube I could find(the plastic flexible Q-tip, and it had an extremely small diameter). I did the exact method described in this thread(angle cut at the bottom, top of tube about 2mm below the top of cart) and the only thing that happened for me was this. If I held the e-cig vertically with the LED facing upward, the hit was above average and flavorful. However, as soon as I turned the e-cig vertically downward(with LED end facing down) air would rush into the cart and close to the entire content of the cart would empty into the atty. I could hear and feel it occurring. I then had to take the unit apart and blow out the atomizer. I'm not sure what I did wrong?
If you keep the straw end below the polyfil and don't overfill the cart this wont happen. It has happened to me but it always was that I simply put in too much liquid. If you put in more liquid than the filler can hold it will look for somewhere to go and gravity will help.
Kevin