Neither you could sell a book, neither he would remain. But if he buys a book that is the real successful preaching. That is the certificate of my Guru Maharaja, if someone, brahmacari, would sell a one paise magazine, if one of our brahmacaris would go and sell a few copies, he would be very very glad and say "Oh, you are so nice!" So distribution of literature is our real preaching. Now if you cannot handle the matter nicely, that is your fault. But the success of your preaching will be substantiated by how many books are sold. Anything you want to sell, you have to a little canvass, so he gives some money for the service of Krsna. That is his good luck and he gets the chance to read some transcendental knowledge. But if you only irritate and he goes away, that is your less intelligence.
The fact is that we have to adopt the same tactics as ordinary salesmen adopt, but the difference is we do it for the satisfaction of Krsna, they do it for sense gratification. Actually we have experienced that sometimes out of sentiment someone gives to ISKCON and then laments and wants it back, but that does not mean we should give it back. Our policy is that his money which would have been used for purchasing cigarettes, liquor, sex literature, meat, will give him the opportunity to gradually become purified. So if by tactics we save that money from being spent on cigarette packets, that is good. If we can take some money and give some literature, that is a good service. So far irritation is concerned, a child is also irritated when he is given instructions, but that does not mean that we should stop. Invite them in our feast, that is a better indication.