Idiom: there's the Rub?

[Andreana]

Hi, could you please tell me how popular this idiom is:

There's the Rub!

I understand it means that's the root of the problem/that's the really important issue and I'd like to know who would use this phrase. I mean, is it used in business conversations for example?
Thanks
A
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A smile will open doors

[Alan]

Hi Andreana,

I think it would be used more in general conversation. Two people talking about going on holiday. One says: I'd love to take a world cruise but I just can't afford it. The second replies: Ah, there's the rub!

Alan
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English as a Second Language
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[Andreana]

Hi Alan, thank your for your immediate response. So, there's the rub sometimes can have a similar meaning to that's the catch?
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A smile will open doors

[Alan]

Hi Andreana,

Not really the same. Let me give you an example. In today's London TIMES newspaper there is a supplement with details of hundreds of hotels/restaurants in the UK advertising EAT OUT FOR ?5.00 per head. The catch is that the ?5.00 refers to lunch because the evening meal is ?10.00 per head and you have to collect the coupons from copies of the newspaper for the next 3 days. Still I suppose it's still good value.

Alan
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English as a Foreign Language
You can read my EFL story Colour Idioms

[Andreana]

Yes Alan, ?10.00 per head for dinner is quite a bargain. Thanks for clarifying the catch issue.
A
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A smile will open doors