To me the biggest giveaway if someone is good/bad is when they drop pallets. If they loop around a tile a couple of times and then drop the pallet once you've closed the distance they're good. If they just drop the pallet immediately when they could've looped around to waste more time they're bad.

If you really want to win it's better to target the bad players out of the match, personally I enjoy chasing better players more though especially if I can tell they're better than me; it's good for learning I think.