I'm the friend mentioned, it's not a huge issue but I really don't want to have to block users just so I don't see their mass spam of the same characters in the trading tags every 12-24 hours.
This is an issue that has bugged me and my friend.
We try to look on the trade listing for new characters but there's this one user who constantly renews all their characters every day or sooner. We ended up having to block them so we could see characters other than just theirs.
My suggestion is to have a cooldown in place to stop users from spamming the un-list then re-list button. (Maybe set to 48-72 hours)