Originally Posted by spot
I think the correct answer is that it would be legal unless the person on the other side is in position to hit the ball and doesn't do so because you are hindering their ability to swing through it.
I am not sure about that. If you are standing in a legitimate position on your side of the court, I don't see that the opponent can claim a hindrance just because s/he cannot do a follow through. What if, instead of blowing on the ball, you hit it with your racquet? You are still in a position right up against the net - are you saying that the opponent can claim a hindrance if unable to perform their follow through without hitting you? This specific situation is not addressed in the rules, but it doesn't sound like a valid hindrance to me.