Hi again PG,
You have talked about a lot of great YC founders. You've also pointed that there have been others who weren't so great. Those who taught you how to do better by not picking founders like them.
Could you please elaborate more on those? Who they were, what were they like, what you learned from them? You sound like a positive fellow who sees the best in people. Why were these folks the wrong type?
I can't say we've learned general rules for avoiding bad apples. The best we can do is to avoid funding people who remind us of bad apples we've funded in the past.
There have been surprisingly few though. We spend a lot more time during interviews worrying about which people will succeed or fail. Out of 170 interviews last batch, there were probably only 2 or 3 cases where we worried about a founder's character.