Quality system, make poor recordings sound better?


I notice that as I move up the audio chain, poor CD recordings sound worse and the good ones sound superb, should this be the case? Also I on any given day my system sounds different even with the same CDs. Any thoughts on this as well?
phd
the recordings must have sounded good to someones ears . more than one set of ears will hear a recording before it is pressed . how does a poor recording get let by ? cheap radio shack equipment in a major studio ?
bands can take years in the studio to make records. you think they are going to let crappy produced music out ? There has to be some kind of quality control. Some times it gets redone by a different producer if the record company or artist is not happy with the final product.
A good system should clearly highlight the differences in recording quality, but it shouldn't make a significant number of record sound so bad as not to be listenable. It would be kind of a foolish hobby to end up with an expensive system that makes the majority of your record collection sound bad.

Throughout the day your body is in a constant state of flux and it effects your ability to hear.

Radio Shack mixers in "good" studios? Please.
I could see live venue recordings having sound quality all across the board . Not controlled environments to mic up and room acoustics playing a big part . IE Classical and jazz recordings