Search results don't show a preview of each search term unless the terms all happen fortuitously to be in the question title or, apparently, close to each other.
For example, if I search for search preview, I see the image below. Notice how the fifth result only shows the context for one of the search terms.
The problem is most noticeable if search results are sorted by something other than relevance. If, on the same search, I switch to vote precedence, most of the top 50 results don't highlight either of the search terms, and none of them highlight both.
Is there a reason for this behavior? It would be more useful if, for each result, I could see a snippet showing the context in which my search terms were matched.