WYSIWYG+CKEditor outputting span with style attribute
So i might not have the most informed answer, but i think i have a solution:

I face the same problem on our D7 site.

It turns out, if you use Chrome, content you paste in the WYSIWYG usually gets these strange line-spacings. (Regardless of if you choose "paste as plain text", or copy-paste from Notepad).

Use Firefox - and you wont see any &lt;span style="line-height: 1.538em;"&gt; stuff in the HTML!

If anyone knows how to use Chrome and not have these span elements show up - please let me know!

Cheers,

R