In bid window right click on bids to mark them as invalid.
Invalid bids need to be grayed out.
All the max/2nd price calculation should skip those

This is no longer an issue especially with auto-open based on fact if someone can use the item

This should be reviewed as generic Auctioning UI upgrades (Master Looter)

I don't like magic clicks, use right click for context menu.
Then add a mark as invalid there?