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Pretty much the only time Google will show your meta description is if all of the keywords in the user's search phrase are found in the meta description. It's why I optimize my title element first (should contain the 1-3 keyword phrases your URL is targeting and most likely to rank for if you're doing your job well).
Once I know what my title element looks like I then optimize my meta description so that it uses hopefully most if not all of the individual keywords from the title. This should maximize the percentage of time that Google actually displays your meta description as the snippet....
So it could be one factor so create correct sentences by using punctation marks like ending periods and commas.
joined:Apr 26, 2012
Syntax, orthogrphy, grammar, s-v-o is not considered by the algo, but there may be personal tester checking your site who consider these things then.