Normally, when referring to sound, most of anything will be subjective to individual hearing perception. But as a general, anything that sound "good" will be connected properly, in the proper alignment and environment, given the proper amount of abuse(again....subjective), and impedance matched with the other components, and having minimal distortion levels. These are the very basics of "good" sound, along with many more variables. Basically, anything produced from a manufacturer is meant to be good. Yes, you will run into purchasing equipment that you are not fond of, or wont hold up to par with your listening preferences, but that;s just it, it's mainly based on an individuals preference. Or even so, a community's preference if the knowledge of "good" is limited to high end audio equipment and lots of power. So, really, if the equipment is working properly, and is connected properly, it will perform as it should, which is good. Anything else, like electrical or thermal, or mechanical issues are not things that people look for obviously or try to produce, for those in business, but it happens. Like creating an amplifier with high distortion levels, or overrating their power capabilities. Those are things they do to get by, but those would be the things considered as "bad" in this case. I do not believe in purposely bad audio or sound. I believe that the knowledge lacks int he field, which creates this "bad" sound simply by messing up the intentions of the original equipment.
Now, as far as just acoustics, again, no flaws are really existent. Even resonances are used in positive manner in some cases. But being physical in a sense, if it exists, its not bad. Sound-wise, bad means incorrect or improper or abusive. We create the "bad" in sound, not sound itself. So, for choosing equipment, base it on subjectivity alone as anything will actually suffice in basic operation as it is intended, for the most part.