"free" trades on trading post

hello fellow Neopians! I was recently able to get back into my 25 y/o account after last accessing it in my teens (🥹) and have been trying to get back off the ground and back into the game. Unfortunately I inherited most of my cool pets and things and don't think I was actually very good at the game so I don't have a lot to my name any more. I noticed people frequently post "free" trades on the trading post but I don't seem to get anything even if I bid within the first couple seconds of them going up.

Am I missing something? Is there something specific I should be bidding even if a trade is "free"? Is it just the case that there are so many people looking for free trades that the likelihood of getting one is super slim? Looking for any advice or wisdom anyone has!