Vig is always there, at least within the same shop. If you bet 250 to win a hundred and a hundred to win 230, you'll break even, or lose 20, and thats the vig.
Its the theoretical edge that the house holds. It means nothing from game to game, while it means everything at the end of the season.
Unless you can find 250 (or less) to win 100 and 100 to win 250 (or more) then you are playing into vig, which you will lose without good luck.
-lab