I'm thinking about how much effect the non-Joss writers of Buffy had on its awesomeness. Obviously, Joss is a genius. That's not under discussion. But what about the other writers, directors, and producers? What can I discover by looking at their eps?
Marti Noxon is first, because Marti Noxon got so much grief for season six. Fans all over fandom either blamed or credited Marti with the darkness, the SM overtones, etc. They even said Marti had the hots for James Marsters and that why Spike was so naked. Was it really her? Was it good or bad?
Marti wrote or co-wrote 23 of 144 episodes of Buffy. She was active as a writer in seasons two through seven. Here's her list of writing credits:
1-2: What's My Line: I and II (2.09 and 2.10)
3. Bad Eggs (2.12)
4. Surprise (2.13)
5. Bewitched, Bothered, and Bewildered (2.16)
6. I Only Have Eyes For You (2.19)
7. Dead Man's Party (3.02)
8. Beauty and the Beasts (3.04)
9. The Wish (3.09)
10. Consequences (3.15)
11. The Prom (3.20)
12. Living Conditions (4.02)
13. Wild at Heart (4.06)
14. Doomed (4.11)
15. Goodbye Iowa (4.15)
16. New Moon Rising (4.19)
17. Buffy vs. Dracula (5.01)
18. Into the Woods (5.10)
19. Forever (5.17)
20. Bargaining, Part 1 (6.01)
21. Wrecked (6.10)
22. Villains (6.20)
23. Bring on the Night (7.10)
She only directed a couple of episodes: Into the Woods (5.10, the one when Riley leaves) and Forever (5.17, the one after Buffy's mom dies). Marti acted as a producer (first a supervising producer, then a co-executive producer, than an executive producer) for much of the show, with what I would assume to the be greatest influence in seasons six and seven, when she was the executive producer.
Blaming her for the darkness and sexuality of season six, then, makes sense, to some degree, since she was the EP. Her writing credits, however, include some of the saddest Buffy episodes, and not all of the smuttiest ones. Yes, she did Wrecked, but that was the only Buffy and Spike ep she wrote, and it's the only one of that period that I remember them NOT actually getting it on in. And she also wrote heartbreakers like I Only Have Eyes For You and Forever, and romantic heartbreakers like Surprise and The Prom. She's been responsible for some silliness, too, including Bad Eggs and Bewitched, Bothered, and Bewildered. She also wrote the final two episodes dealing with Willow and Oz's relationship, Wild at Heart and New Moon Rising, which I hadn't noticed before and think is very interesting.
Basically, it seems to me that Marti gets a bad rap for no real reason. Since I more or less like the direction the show went while she was the EP, it's not surprising that I'd say that, but I really don't see evidence otherwise in her list of writing credits. I will admit, though, that she likes to tie up and torture both Spike and Angel, being responsible for Angel's torture at the hands of Spike and Dru in What's My Line II and Spike's torture at the hands of The First in Bring on the Night.
Incidentally, my favorite Buffy line ever is from Bargaining 1, so Marti also wrote that.