I once had a pair of ICs that seemed fine, and then after moving some components around and unseating and reseating the cables, I found that they were unusually bright sounding. I sent the cables to the manufacturer who noticed nothing wrong on initial inspection.
There was some discussion about cutting the cables to a shorter length and re-terminating, and it was when this work was being done that the manufacturer noticed that a ground wire had become loose. So on initial inspection nothing, and then after looking more closely, yes, a problem. Happy to say that the cables came back in excellent condition and performed flawlessly after that.