Oddsmakers are highly trained and very experienced in their profession. They know what teams draw the most money year in and year out. Through the years those teams have been the Dallas Cowboys (the self-proclaimed “America’s Team”), the Green Bay Packers (who may have more fans across the United States than any other team), the Pittsburgh Steelers (an incredible die-hard fan base) and the New England Patriots (mostly because of their incredible scent success).
In years past you could have added the Oakland Raiders and San Francisco 49ers to that list. A hard time has hit both of those California teams, so even their most loyal fans have shied away from putting good money on them. But the Cowboys, Packers, Steelers, and Patriots are still well-bet by their fans and by people across America.
What that does is inflate the line at times. For instance, the Cowboys might be a seven-point favorite at home against a team such as the Miami Dolphins. But in reality, the line should really have been six, or even less. That also means you can some times get a bargain by betting against those teams.