I guess the reason we call Quartz sprites bad nowadays because we have a new style and most of us believe that the new Black & White sprites are the epitome of Pokemon sprites. We pay too much attention to the new sprites and we end up comparing all of the new fakedex's and new fakemon to the current official style. But I think the concept is very important as well when it comes to judging a sprite because I remember seeing Babos from Pokemon Quartz and that thing was... unusual.
I do not think Baro's style of spriting is bad. It's just that his Pokemon seemed to look... out of place, to understate it. His spriting skills are actually quite good, if you pay attention to his shading. And I do not mean "bad" by my opinion, just by the general community(But then again, I did use youtube for feedback, which was likely my biggest mistake.) So basically, in order to make a "good" sprite you need to pay attention to your audience? Perhaps I should put a few of my sprites in display to get some feedback. I haven't decided whether to create my own style or to attempt to create a Pokemon-ish one yet.