There is another thread, right on this page, discussing this same topic:
http://forums.studentdoctor.net/showthread.php?t=713138
The answer is that there is no clear "definition" of malignant. One person declares a program malignant. Someone else at that program says it's fine, and that the complainer is simply angry/vindictive/etc. Some programs may terminate more residents than others -- does that mean they are "malignant"? Maybe, or maybe they just have tougher standards to which they hold. Or maybe they take weaker residents (giving them a chance) and then have a higher rate of failure. Who knows?
Some people look at it by workload. One program has you managing 20 patients at a time. Another only has you managing 12. Is the one with 20 malignant? Or perhaps they simply think that managing more patients teaches you more -- and maybe it does?
Some look at it by ancillaries -- how much support is there for residents? Do they have to do their own blood draws, or schedule appointments, etc?
Really in the end it comes down to how residents are treated. If they are treated with respect, that's good. If they are treated with disdain, contempt, or indifference, that's going to lead to problems. But getting anyone to agree even on this is impossible.