Smell does not escape !
I have had my Dicky bag a while now and I have not had a single split poo bag since. I store a ball in it when we set off; the dog carries the ball home and by then the bag is full of poo.
I have the extra large bag 2 collies and a heinz 57 it is easily big enough. Most impressivly, I forgot to empty it last monday and 7 days later the smell had STILL not escaped from the bag!
I am so impressed with the bag that I have stopped people on walks who are struggling with poo bags to tell them about it.
You must remember to grip the air freshener when you empty it though or it ends up in the bin with the poo.