If I can do something for you and you're not a twat, I will. I expect the favour returned.

As for persuasion, well. I am a saleswoman by trade at the moment, and I hate it. I'm there to exchange currency, but along the way I am required to make you take extras. My persuasion technique is all distraction, and will be based mostly upon your gender, followed by your age. I have morals, you know. If you're a kid, I play the nice exchange lady and don't bother with the extras.

With men, especially the middle aged ones, leaning is the most important part. When offering the rip-off extras, I lean a little over the counter, and suddenly they're not looking at my face anymore. I say my bit, then jump back and nod vigourously, and then they start nodding vigourously too. It is clockwork, so much so that it makes you doubt in humanity after a while. If they look like they might be difficult, ask them beforehand if they're away on business; when they respond with the inevitable 'yes,' smile a lot while telling them how busy they must be. Do you get much family time? Oh no, me neither, my dad's an executive for a car company, he's in India all the time. In those cases they project their own children onto you, and take the extras they know they don't need out of sympathy.

With women, I try to let them know that I'm either their equal, or smarter than them, pretty early on. It's the only way to get them to trust me. Our male salespeople have to do the same with men.

When you're buying something that isn't just groceries - be it a phone, currency, a computer, a book, anything - know that the salesperson will have you sized up. If they're really good you'll leave feeling something - happiness at the good deal, impressed by their acumen or intelligence, sympathetic to their cause or situation. People like to think that they're immune to salespeople. I hear it all the time. 'Oh, ha, that'd never work on me.' It would, and it does, and until you've worked in it you can't really be prepared to combat all the trouble a good salesperson will give you. Their pay depends on convincing you to take the shit you don't need, and they will get there. I do it all the time, and it makes me feel bad, to fleece people with a smile, a nod, a lean, and a conversation.

There's only one way to deal with them, and it sucks - but be rude, be brusque. If they can't raise a smile from you they'll give in extremely quickly and leave you be, but not without trying to make you feel slightly guilty about it. Don't give in. Let it be known that you're just there for business. Doing that is a lot harder than it sounds unless you're a twat.