Sam's ulterior motives
I have started to rewatch this series. I'm only on S1E03. I really do not know what Sam's issues are. I think Brooke is very kind and nice when she lets her guard down - and she even makes attempts to make peace as much as possible. Brooke is never really after Sam; Brooke only acts means when Sam provokes her.
Sam, on the other hand, is selfish, egocentric, and thinks herself as unique (there's lots of "unique" people dressing around like Sam). She has a personal crusade against Brooke, and will do anything to bring her down though Brooke has really not done her any real harm.
I'll keep watching. I really enjoyed this show when it came out, though at the time I was in Belgium and watching re-runs by 2001-2002. I'm glad for Youtube! I never watched more than 5 or 6 episodes I think.