I think in this objectivist forum most accept that if it measures beyond a certain level the item will be pretty much transparent. Measuring "bad" is a relative term. Even a relatively "bad" measuring product can be sufficiently transparent to be un-noticeable to subjectivist audiophiles that are often hopelessly optimistic about what they think they can hear.
Thing is for a manufacturer to release a poor performing product doesnt make much sense to me when it is clearly possible to produce superb performing kit at very reasonable prices. Making a poor product isnt necessarily cheaper, so what is the advantage of doing so?
Due to the high level of performance and transparency of most electronics (ignoring speakers), perhaps the only way to differentiate a product by subjective sound "quality" these days is to deliberately make it have audible performance defects. It needs to have a "character" and not actually be transparent. In similar vein to TVs having a "shop" mode with over saturated colours, brightness and contrast to make them stand out.
I agree 'bad' is relative.
I can't prove this but given some of the 'trade' contributions to this forum where their products have been measured and found wanting in various areas, it seems there are a few possibilities.
Lack of competence and equipment. We (general) tend to assume that the producers of products are competent in their field and test what they produce, and test for the right things. We, the consumer seem to have this idealized vision of those who produce audio equipment spending countless hours testing, developing and listening to what they produce until as near to a state of perfection is reached. I know, that some designers don't use, test, or listen, in the case of audio equipment, to the final product. They don't need to. The physics and calculations are so well understood that listening is unnecessary and so is much of the testing.
Particularly in audio it seems that some designers get locked into a particular mindset about how something should be made; those who swear that a valve amplifier will always sound better, those who are locked into class A equipment, others who believe that a music server kitted out with linear power supplies etc is going to sound better than a laptop.
So, it's not often a question of price, it's a question of conviction in the above.
If I may, without causing offense, take yourself as an example. From what I've read your products perform far beyond what is audible. You have a few posts where you've gone to the trouble of producing a rather nice milled aluminum enclosure for a dac I think.
On a much more modest scale, I've built a number of loudspeakers for people I know. I have no measuring equipment at all now. I build from data and experience. In order for me to test and develop say a loudspeaker and provide any specifications regarding their performance I would need to acquire a lot of measuring equipment and spend countless hours doing the measuring.
The notion of the angst ridden audio designer sweating over whether or not a particular type of capacitor sounds better than another is largely an audiophile fantasy.
Rationality doesn't seem to feature big in audiophile circles.
It is true to some extent that making a poor product is not necessarily cheaper. Illogical though this may seem though, making an excellent measuring product is considerably more expensive because of the necessity of development to achieve this.
The Audio GD is not a poor product imo. It's on par with many of the products in its range. It's easy to let the outstanding performing products blind us as to what the average is in fact like.