I was aware of Pulaski's mean-spiritedness towards Data, but I never realized just how extreme it was until your thoughtful and eloquent analysis of it there really put it into perspective.
Coincidentally, Pulaski seemed to finally realize the error in her judgment of Data right before she left the series for good. I'm referring to "Peak Performance", where she goes to his quarters and tells him to "stop sulking", admitting to herself and to him that Data is a lot more human than anyone gives him credit for (including Data himself). I think it was Pulaski's best moment on the show, and probably the only one in which I really liked her. Not that it made me sad about her leaving after only one more episode.