Anyone - is there an industry standard concerning dashes? I mean the use of en and/or em dashes?
Just on visual terms, I dislike the em dash when it's used without spaces. It looks like a rigid bar that's been squeezed in between your two words, poking both. Ouch.
The en dash with spaces is much better looking.  

Use sparingly and one - should suffice. 
 

I think em dashes are rare in British publishing but more common in US publishing, where they are usually used without spaces either side. 

This post sums up the way I have dealt with them: http://www.karlcraig.com/dash.html

In manuscripts, or in typesetting?

In manuscripts, it doesn't matter because the copy-editor will mark it up to tell the typesetter what to do, to conform to that publisher's house style.

If it's you getting it camera-ready (OK, I know it isn't cameras these days) then New Hart's Rules says, after the obvious stuff about closed-up en rules for joining words:

"Many British publishers use an en rule with space each side as a parenthetical dash, but Oxford and most US publishers use an em rule [...] closed up"

And everyone uses an em rule closed up, for an interruption at the end of a sentence.

And everyone uses an em rule closed up, for an interruption at the end of a sentence

And now everyone includes me.

Thanks for the replies.

You're welcome, Alan.
 

I read recently that the colon and semi-colon is old fashioned and falling out of use and should be replaced by the dssh. I've noticed that a lot of Blogs and new fiction now follow this preference.

I read recently that the colon and semi-colon is old fashioned and falling out of use and should be replaced by the dssh.

Such rubbish, whoever said that. I do hope you won't believe them, Maricellus! . Why stop using a piece of punctuation that's extremely useful and precise? Precision matters in writing, or we lose the ability to make or words work on the reader as we want them to. Just because some people don't care to use them doesn't mean anyone else should stop.

The dash is useful, because it's vague. Sometimes that's what you want, especially when your writing is being inflected as much by how things are said, as by the meaning of what is being said. That's often the case in fiction and creative non-fiction, just as it is in relatively informal forms such as blogging

The dash is also disastrous, because it's vague: it doesn't express the connection between things, only that there's some sort of tiny pause. Colons and semi-colons express how the two things they join are connected: they're all about meaning. 

There's a school of thought that you shouldn't use semi-colons in dialogue - and perhaps not colons either? I sort-of agree - at least, I see why it's said. In dialogue the sound-expressing function of punctuation gains in importance, and sometimes that should trump the meaning-expressing function.

But if you use dashes a lot - to represent different things - sounds - meanings - then the sense of what's being said soon begins to break down. That might be appropriate in any given bit of dialogue, if the speaker really is becoming a bit incoherent, or they're fumbling for what they're really trying to say. But it is something to be careful of. Less is more in this case.
Edited by EmmaD at 12:24:00 on 17 May 2014

Furthermore, I maintain that working in a well-positioned semi-colon is a bit, umm, well, orgasmic. It is for me, anyway. Colons are merely a quick thrill.
Dashes are a poke in the ribs. En dash a little one, em-dash with a iron bar.  

Well I searched my web history and Evernote database but I cannot find the article. What I do remember is that the author of the advice was American ( and that has nothing to do with it in any way ) and it was a piece about self-publishing or indie-publishing. I think the point they were making is that a lot of readers do not know how to interpret the colon and semi-colon nowadays.

I think you make your point most succinctly with this quote in your reply.

But if you use dashes a lot - to represent different things - sounds - meanings - then the sense of what's being said soon begins to break down.
 

you make your point most succinctly with this quote

I wondered if anyone would notice!

LoL Alan! Do you know this blog, and the book? Bliss for punctuation nerds:

http://www.shadycharacters.co.uk/

Do you know this blog, and the book? Bliss for punctuation nerds

No, I didn't know it. I don't think I'm nerdy enough to appreciate it, to be honest (very serious about punctuation, actually). Or I'm just not on the same wavelength. I don't know. But thanks for the link.