writing for another site - use rights questions

I was looking at guest blogging for another site.  They do good work and it would be a way to gain visibility and reputation as an author.

But on reading the fine print, they want exclusive rights to any content I give them.
- they can edit it as they see fit, without informing me.
- I can never use the writing anywhere else.
- they can produce it in any way they want.

In exchange, I gain visibility and affiliate income.

I'm not sure how to feel about this.  If it was print media, I would be fine with agreeing never to use the material elsewhere.  But I like the idea that I can take a paragraph I publish one place, edit and incorporate it into another work, then give citation back to the original place I published it.  

But online media with them being able to edit anything I write without my approving the edits... Why would this be something a site would want to do?  Is there any way this works to my advantage?  Maybe I'm just being suspicious.

Sounds like a "work for hire" agreement, which I advocate you avoid like the plague!

I agree with Tyler and am very suspicious too and it sounds like a terribly one-sided agreement. I believe that if it's your material, you should have the right to edit as you see fit, use anywhere you desire, and publish it anyway you choose. I think they should be honored to have your work. I couldn't imagine a songwriter relinquishing all rights to a song they wrote.

What if you would:
- write the article on your own blog.
- and publish a short summary (1-2 paragraphs) on the other blog?
- link from the summary to the full article.

They are exercising far too much editorial control over your copy. I can begrudgingly allow a skilled editor to write a new headline, but to alter the copy for anything other than style is not something that a respected journalistic outlet should do. I'm not familiar with the outlet to which you're referring, but I know many blogs simply lifted the editorial policy from some other source and used it going forward. It's possible they may be open to negotiation for your content in a private agreement. I would approach them on that point and if they were inflexible, I would not contribute to the outlet. Here's the editorial policy I use when I publish my blog and magazines:

Xxxxxxx’s editor happily accepts by-lined editorial submissions with the right of final editing for style and length. Submitted editorial content remains the intellectual property of the submitting author. Editorial and graphical content of Xxxxxxxx may not be used in any form, printed or digital, without permission of the editor and requires attribution.

Just a few thoughts for your consideration.

Looking back at this a few years later.  
I am glad I didn't do it.

I'm okay with copywriting - writing without my name being on the item.  

I'm okay with writing for others, with my name on the item, so long as I get final approval of the edits.

But I'm not okay with my name being on the item, and the words being edited by someone else with an agenda.  

The site I was looking at is still up and publishing, but after all these years, it's still riddled with bugs.  I looked at an article published today and it has a huge error note.  

WARNING: unbalanced footnote start tag short code found.

If this warning is irrelevant, please disable the syntax validation feature in the dashboard under General settings > Footnote start and end short codes > Check for balanced shortcodes....

followed by a bunch of code.  It's the kind of error I see a lot in WordPress sites that use out of date templates.