So, how do we fix our faulty, bone-jarring lack of correct intonation?
First, acknowledge that the problem may actually by our own, not the other guy's.
Next, determine to examine each note with the honest help of a tuner.
Then, correct the pitch without losing the rich core of the sound.
Play musically but play in tune. Playing musically but out of tune is not playing musically. Unfortunately, this is a lesson that must be relearned daily.