What makes Irn Bru so refreshing?

This is cross posted but hopefully I have cunningly changed the language so much you won’t see where. If you do then please PM me so I can do something about it.

Anyway, onto the thread itself - what is it that makes Irn Bru so amazingly refreshing?

It cannot be any of the following:

[ul]
[li]Sugar[/li][li]Caffeine[/li][li]Quinnine[/li][li]Ammonium ferric citrate[/li][/ul]

More or less anything else I’m willing to consider - but the above cover almost everything in it, paradoxically. So what is this trace ingredient that makes the world ok?

Refreshing? I have tried it once (or rather twice at the same time; first and last) out of curiosity and found it truly horrible.

Alright, I’ll say it and we can get it over with:

Girders.
The real answer: water and sugar. Why would it be some mystic trace element?

I’ve always assumed it was the taste of the enamel that Irn Bru strips off of teeth upon contact.

Damn.

It gets the taste of Bucky out of your mouth.