The answer is simple: when you call on him or her.
Some buyers acquire a reputation for being tough, overbearing, demanding—just plain impossible to deal with. And guess what? Salespeople stop calling on them. Why put themselves through the abuse? Why endure the indignity? Why indeed, you may be thinking.
Why not? They have to buy products and services from someone. It might as well be you. A prospect may be demanding, discourteous, and disrespectful. However, beneath the gruff exterior, there is a human being capable of listening, evaluating, and making decisions—buying decisions.
Remember, you too have an exterior—your salesperson persona. When you call on the impossible prospect and he “attacks” you, it’s only your persona he is attacking. So allow your persona to don an invisible suit of armour. When you call on Mr. Crotchety, you’re Sir Lancelot. Nothing he hurls at you can hurt you. You’re protected. Sure, you armour may get dented, but the order in hand will have made it worthwhile.