If the engineer does a lot of live stuff, then it might just be a bad habit on his part, boosting the 120-200hz which often sounds cool live, but not so much in a studio setting.
I had a Sadowsky UV-70 V which I used for some hardcore/metal stuff, and my problem was always the opposite; To bright - especially with a pick.
If you´re running things through a distortion pedal, it might be a type of distortion that distorts on the "dark side" which can make it sound muddy, but IMO it could probably be fixed through some quick EQ settings.
I had a Sadowsky UV-70 V which I used for some hardcore/metal stuff, and my problem was always the opposite; To bright - especially with a pick.
If you´re running things through a distortion pedal, it might be a type of distortion that distorts on the "dark side" which can make it sound muddy, but IMO it could probably be fixed through some quick EQ settings.