Okay.

I disabled bookmarking to remove all blue lines.

Left as is, it provides a handy way to spot the never played.

Hmm, just seeing that it is againts the previous feature request to show the played mark for already played episodes:
https://www.ventismedia.com/mantis/view.php?id=16166

Hi,
thanks for reporting, tracking as https://www.ventismedia.com/mantis/view.php?id=20448

Per this post https://www.mediamonkey.com/forum/viewtopic.php?t=105291 complete blue underline is displayed only when Enable bookmarking is checked off as enabled. This provides no added value to users and becomes screen noise. Please only display this underline for partially played files. With this being the case, it should only appear for files pending completion. If a user has not allowed a particular file to compete playback and instead skipped to a new file, only then would I expect multiple blue underlines for time.