When you view the homepage of any SE site as plain text, the tags run together. For example, the homepage of ELU has this near the top:
single-word-requestsmeaninggrammarword-choiceword-usageetymologygrammaticalityphrasesexpressionsphrase-requests more tags
There should be spaces between the names of the tags. Elsewhere on the page in plain text, tags are displayed properly separated by spaces. Note that this isn't visible when I visit the site normally, view it as "rich text", or try to print it (but the print view is very messed up for another reason).
Why does this need to change? Because that's how Google sees the page. For example, try this search.
(This is definitely a problem on SE's side, not Google's. I'm able to reproduce this problem using the "plain text" option in the "Get Text From Webpage" Automator block, which shows the entire page, although you can't use the site like this because plain text doesn't include links.)