When does one become a "customer"?

[mjr]

I know when a lot of people think they become customers, but when do you think someone actually becomes a customer?

If someone walks into your establishment, wanders around, doesn't buy anything, and leaves, that doesn't make them a customer.

If someone comes into your establishment, asks questions, and might buy something, that makes them a potential customer -- but not a customer.

If someone calls you on the phone, asking you for a price on something, they're not a customer.

So in the cases above, you can't really provide "bad customer service" to someone who isn't a customer. Right?

So what about you? When do you think someone becomes a customer?

I mean, dictionary.com defines it thusly:

http://dictionary.reference.com/browse/customer?s=t

So unless you go by the "patron" definition, or definition #2, I don't see how anyone could be considered a customer unless they purchase something.

That said, even the definition of patron appears to have to do with actually spending (or supporting with) money.

[Aria]

I think you are officially a customer when you spend money. Even a dollar will do. Although, that doesn't make you a worthwhile customer... XD

[MoonCat]

Most businesses will want you to consider anyone who shows even remote interest in your business as a customer. Potential, actual, they don't care. They just define the whole world as "customers."

I can accept that to a point. Where I draw the line is when I spend way too much time helping someone who then decides they are not interested. And as for people who shoplift or go into stores and trash the place, those are not customers, they are scum and should be treated as such.