Badminton is my alternative sports betting but it's very difficult to find value odds because in badminton the competition is not like other sports, where unseeded athletes or underdogs teams have a chance to keep winning, while in badminton, seeded players are almost certain to become champions in many tournaments.
I played badminton for a very long time and in the past tried to find good bets on it, but as you mention it is hard. Most of the times, the topseeded players will always progress and their odds are pretty low most of the times.
This is a problem for almost many bettors, they find it difficult to determine what match will make a parlays bet win, sometimes they think choosing lots of small odds will give them a win but small odds for teams or athletes don't always win, sometimes we think it must be the right match but it turned out the other way around. Often experience this in football and tennis matches, so sometimes it's better to stick with just a single bet and if you want a parlay, only with a small bet value so you don't really feel like you're losing when you lose, at least I've won 1 or 2 times at parlay but the comparison with the losers is very different.
What happened to me most of the times, is that the bet with the lowest odd always was lost and I would often end up with 3/4 or 4/5. Yes, you can have some winners, but in the end, It doesn't end up in profit.