This website is awesome if you think lists and rankings are in any way fabulous which they are. I'm going to use this particular list to get a generally accepted bottom ten episodes and it certainly looks like a bottom ten:
(10) 135 Reptile Boy (David Greenwalt)
(9) 136 Some Assembly Required (Ty King)
(8) 137 Inca Mummy Girl (Matt Kiene & Joe Reinkemeyer)
(7) 138 Go Fish (David Fury and Elin Hampton)
(6) 139 Beer Bad (Tracey Forbes)
(5) 140 Teacher's Pet (David Greenwalt)
(4) 141 Bad Eggs (Marti Noxon)
(3) 142 Where the Wild Things Are (Tracey Forbes)
(2) 143 I, Robot...You, Jane (Ashley Gable & Thomas A. Swyden)
(1) 144 Doublemeat Palace (Jane Espenson)
The first thing to note is the sheer number of absolute stinkers there are in S2. The second thing to note is that David Greenwalt has two episodes there and he was the showrunner on Angel for three seasons. Just saying. The third thing to note is that two of the episodes have so much to like about them that I can't hate them (plus there is my soft spot for "I, Robot... You, Jane" just for Willow hitting Moloch with a fire extinguisher and shouting "Remember me, your girlfriend?")
So "Beer Bad" has a heavy handed anti-alcohol message but cave girl Buffy is hilarious plus the "Gutterface" scene and, of course, let's not forget the most important message, "Fire bad!"
But I have a strong liking for "Where The Wild Things Are": if you remove the seemingly endless sex (and ignore the issues of informed consent), it's a good episode because there is funny stuff like Xander and Anya arguing in an ice cream van, Spike and Anya getting chatty, Spike remembering he was evil and going off to watch Danger Mouse, Giles singing, Xander being brave and, best of all, from my point of view, some lovely Tara and Willow development.
"Guaranteed safety and fun". (Amber's hands look huge in this scene on the stairs.)