I dont try to "fix" any recording. I accept the imperfections. Any system that makes everything sound good is a colored system.
Let the best be your guide
All of us have had to come to grips with bad sounding recordings. They can be disabling and make you question your whole system. The trick is to accept them for what they are and not to generalize. I try to listen for the music and skim over the imperfections. When confronted with a clinker, to save my sanity, I play a recording i know to be superior sounding. That restores my faith in the system and brings me back to reality.