The setting: I’m waiting in line at a leading chain bookstore watching an exchange between the clerk and a woman who wants to purchase two books.

The conversation:

CLERK: Do you have a membership?

CUSTOMER: No.

CLERK: We’ll, you really should get a membership. It costs only $25 dollars a year and you’ll receive great offers and savings. It’ll take just a minute to sign you up.

CUSTOMER: No thanks.

CLERK: You’d be saving $4.73 on today’s purchase alone with the membership.

CUSTOMER: I’m not interested, thanks.

CLERK: (in a tone that can best be described as baby talk) I just can’t bear to see you buy these books without a membership. Please get the membership.

CUSTOMER: No thanks, just the books, please.

CLERK: (ringing up the purchase) The membership?

This was a real interaction, to the best of my recollection, although I don’t think I can do justice to how over the top it actually was. I kept waiting for Ashton Kutcher to jump out from behind the counter to tell the customer she was being “Punk’d.” How the customer kept from losing her cool, I’ll never know, but I nearly stepped in with $25 at one point just to put an end to it.

This is the most egregious example of upselling I’ve ever witnessed. But I guess I shouldn’t be surprised. There’s an employee at a different location of the same retailer that I used to avoid because he was so relentless about the membership.

It’s certainly not isolated to any one business, however. Where there’s commerce, there’s upselling.

At the coffee shop: Would you like to make it a large for an extra $.50? How about a scone with your coffee? How about a pound of beans for the weekend?

At the restaurant: Can I get you started with an appetizer? Would you like fries with that? Did you save room for dessert?

At the mechanic: It looks like you’re due for a 30,000 mile tune up, can we go ahead with that? Would you like to use the synthetic oil today? How about a new air filter?

It’s everywhere. Upselling is taught by employers. There have been books written on the topic. “Experts” conduct seminars. And I’m sure it works, if done well.

But that’s the catch — it is rarely done well. Employees are instructed to stick to the script instead of trying to read situation or the customer. It can be such a turnoff that I’ve decided to take my business elsewhere on several occasions instead of dealing with it. And I’m sure I’m not alone.

There must be a downside to upselling, right? If your customers would rather endure an interrogation from Jack Bauer rather than listen to your employees badger them with lame upselling attempts, they’re not going to come back.

It’s risky business trying to squeeze the last nickel out of everyone who walks into your establishment. Call me crazy, but I think happy, repeat customers will be more valuable over the long haul.