qBittorrent official forums

I'd love it if qb could change the color or icon of torrents where no "working" trackers are up. This would help both to make it obvious when a tracker was down, and make it easier to check your torrents for any that had been deleted from a site... at the moment this requires manually going through the entire giant list of inactive torrents one by one.

Are you talking about private trackers? Because with public torrents, just because there is no working tracker does not mean that the torrent will not download.

They are other ways to find peers, especially DHT. This is the reason why qBittorrent does not display any error when no tracker is working.
However, you are not the only one to feel this way (see https://bugs.launchpad.net/qbittorrent/+bug/508435) so I guess I need to find a suitable solution for this problem.