Salary may not be a perfect indicator of team strength. However, I would almost always bet on a team that has 50% more salary than his opponent in BB. Yes, there are some teams that can do well with low salaries - but not ridiculously low salaries compared to their competition.
Even if we look at a real life example, a team that is spending considerably less in salary than the rest of the teams in their division will hear it from the fans. Well, unless they are winning every game. Of course, winning always makes the fans happy. But if they are losing every game? Or even if they are playing .500 ball? The fans would definitely be upset - especially if the team is sitting with a ton of cash in their bank account.
Run of the Mill Canadian Manager