I don't think it would be very accurate to say that a 57 sounds bad through a Mackie board . . .
just different.
Keep in mind a lot of it has to do with Mackie's non-linear response as you approach the extremes of it's gain-staging.
In layman's terms, it likes to be set at about 12 o'clock or so, and as you turn it way up or down, it starts to sound thin and sometimes grainy. The Mackies have a sweetspot, gainwise, where they have good, solid, low-noise, linear response. Venture outside of that range, and the sound changes -- sometimes for the better but sometimes for the worse. Unfortunately, a lot of dynamics like the 57 either need a lot of gain due to their wimpish output, or they need very little gain because you've got it right up on a kick, snare, or a hairsplittingly-loud guitar amp.
A lot of this also has to do with the loading characteristics of a given mic pre. Admittedly, Mackie boards aren't necessarily ideal in terms of loading . . . which often means a less-than-ideal match on low-output dynamics, ribbons, and condensers with transformer outputs.
The good news is that I hear very little difference between a transformerless condenser running through a Mackie at modest gain and the very same through a Sytek, for example. Most modern transformerless condensers just aren't as sensitive to loading . . . and will often find themselves well within the Mackie's sweetspot (and if they're not, a good -10 db pad should rectify the situation).
