First, I'm not one of those scrolling through lists of torrents with an "I want this. I want that" attitude. I'm usually seeking a particular file, do a torrent search, click on a result, select Pirate Bay (they're at the top, almost always have what I want, and give decent information), and look at the stats for that torrent before getting it. If zero seeds are shown I go back and try another; also read comments, if any, to see if others had any trouble (though these are all too often people requesting a different, similar, file to be uploaded).
So, after trying to be practical about what torrents I select, I've still amassed quite a few that either never start or never finish. I get 35%-98% of a file and, no matter how long I leave the download active, never get the rest. I've considered that by foul coincidence I'm never online at the same time as whoever has the rest of the file (I usually leave bitcomet running all night, occasionally for several hours during the day). And, of course, it could just be a bad torrent. Is there anything I've overlooked in the selection process, or is there some way of determining a bad torrent before wasting all that time, and bandwidth, on it?