Basically WYSIWYG editors do their best, but still fail on a number of fronts. One being their use of &nbsp; in certain situations. For example, in newish CKeditors when fixing parts of sentences, adding/removing words, or changing inline styles, it will often insert a &nbsp; instead of a normal whitespace. Another example is the print media or word processing tendencies for people to use double spaces after punctuation, resulting in a whitespace followed by a &nbsp;, which will actually render 2 spaces when viewed. This is opposed to normal HTML behavior, which only displays 1 whitespace, even if multiples are found in a row. Inexperienced content writers don't always remove these &nbsp; and quite possibly don't even know they are there. What results is content that is junked up by these non blocking spaces instead of normal whitespaces.Question is, should we worry about repairing all the injected &nbsp; mess from the editors? Will it have an effect on SEO if they are left in? Should we make special html_entity filters for things like JSON descriptions or shopping feeds, or just leave them alone and hope the endpoint can render them properly?
How do bots/automation treat unnecessary   from WYSIWYG editors?
seo;html;wysiwyg
From Google's Matt Cutts...http://yourseosucks.com/2009/09/5-common-seo-questions-answered-by-googles-matt-cutts/(Point 4)Um. We really don't care that much... Any time we see white space, we'll separate stuff. And we can ignore white space, so it doesn't really cause us a lot of harm either way... As long as you're doing normal, reasonable stuff, I wouldn't worry about it that much.Based on this I would tend so say not a big deal SEO wise. Certainly clean it up if you can as one of the pagespeed recommendations Google makes it to minify HTML and eliminate extraneous white space, but it would appear as though it doesn't make a different to your ranking.