People who hold pro-market views are often tarred as corporate shills. That epithet more accurately describes pro-business attitudes, which are very different creatures.
George Mason professor Don Boudreaux discusses this with his usual eloquence in his twice-monthly newspaper column. Well worth reading, especially for you non-economists out there.
Another thing about such name-calling is that it dodges argument on the merits; it is the highbrow equivalent of ending an argument by saying, “Oh yeah, well you’re ugly.” Which of course, has nothing to do with whether the arguments are right or wrong.