When comparing lineages, how can you honestly and objectively evaluate what good WC is?
I think that most people will always view the quality of WC in general through the standards established by their own sifu. Therefore, we will probably never agree 100% as to what is "good" Wing Chun.
For example, you see many different approaches to chi sao: one school may emphasize that if your hands are moving too much, it is wrong; others may say that if you are moving backward, you are losing; yet others may believe that resisting an opponent's attacks with brute force is wrong; and of course, there are those that believe that as long as you are hitting your partner, you are winning. And on many occasions, I have seen people from different lineages doing chi sao (and it seems to always boil down to a tacit competition in these cases), and coming away with a different conception of who did "better." Or at least, a rationalization of why they didn't do so well (i.e., "he was hitting me, but I was pushing him back the whole time"; "he was hitting me, but he was using too much force"; "he was hitting me, but his hands were flying", etc).
So here's the question: what attributes make good WC?