Betting trends usually refer to what the public is doing. You have two choices, to follow the public or fade the public.
Following trends is always worthwhile in sports betting because you can find out what the general public thinks of a certain matchup. For those that follow trends, one of the more popular strategies is to fade the public. In a basic sense, the public money usually goes to the obvious side of a matchup.
For example, the Baltimore Ravens are coming off a dominant 30-point win and are a -3 point road favorite against the Pittsburgh Steelers, who were blown out by the Cleveland Browns the prior week. On the surface, the Ravens look like the better team and are probably the better team. In this situation, it's possible 80% of the public money is on the Ravens simply because they look like a better team to the naked eye and recent results back that up. However, that's only one side of the equation.
Maybe the Steelers have won the last five matchups between these teams when played in Pittsburgh or maybe they're 9-3 straight up in their last 12 games as a home underdog. These are the kind of numbers the public doesn't usually care about. When a matchup is posted at a sportsbook and bettors see the spread of -3 for an undefeated Ravens team against a five-loss Steelers team, the majority of them will flock to the small spread.
If you back the Steelers +3 in this case, that's fading the public.
On the other end of that, a bettor may have numbers that support taking the Ravens -3. Maybe they have won their last five games by double digits and the Steelers have failed to cover their last five divisional games. After going over those numbers, a bettor could then see the 80% of money on the Ravens and use that as evidence that it's the correct pick. If everyone is on the Ravens, then that must be the correct play.
If you back the Ravens -3 in this case, that's following the public.
Fading or following the public is a personal preference, but it's important to remember that sports betting exists because sportsbooks make money on losing bets. In turn, most of that money is made because of the public being wrong more often than not. That being the case, fading the public may be the best trend to follow.