Help me understand these numbers...

El Sapo brings up an interesting point. But can we really take sportsbook.com's numbers as being 100% acccurate? Why should we believe sportsbook.com's numbers to be the absolute truth? Is it not possible that they are posting percentages incorrectly in oreder to encourage action on a side that they prefer that bettor's take?

For instance I see currently on sportsbook that the Bengals have "89%" of the action. Yet sportsbook opend the line at -10 and subsequently moved it DOWN to -9.5. It seems that sportsbook is either encouraging extremely lopsided action on the Bengals or is being disengenuous about the percentage of action they are receiving on the Bengals.