Vice? Not really. Briefly, I’ve criticized Lu Xun mainly for

1. Buying Bolshevism without bearing in mind this Roman proverb: Caveat Emptor ("Let the buyer beware");

2. Failing to make a serious effort to understand American democracy and capitalism; and 

3. Putting too much faith in radical change by radical means. (According to Lu Xun, if you want a Chinese to open a window in a dark house, you need to impress him/her that you are going to remove the roof; otherwise, no Chinese would give a damn. I would say to Mr. Lu Xun, "Be careful what you wish for.")

OK, I think that's about it.