At the end of almost every japanese dub anime with episode previews I've seen, the previews are confusing to the point of making no sense whatsoever. Usually they are some random character, either major or supporting, saying some things remotely related to what the next episode is about while staying in character. For example, preview for episode 23 of ToraDora. The 30 year old teacher who talks about how she loves chocolate weeeee valentines day is fun. The actual episode is about how ryuji's mom faints from anemia from being overworked in her part time job to help pay for ryuji's future education. Then, Ryuji, Taiga and Ami go take her place. And then drama stuff happens.
Well, most subs>dubs, but there are rare exceptions, chobbits is pretty fun dubbed, too f.e. BTT these previews are short scenes of the next episode with often a NON RELATED mostly funny conversation, sometime they lead back to the next episode though, ... I personally dont like real previews ... Now why, that's probably because they have a different understanding of previews or more accurate: teasers
We've got a dozen or so anime fans/freaks in my year, they're annoying about it to the point where i stopped listening to what they were talking about, since it's about anime 30% of the time. No, i don't care if there's a new chapter released, i don't care if some character died or something. No offense though, i don't hate it, but when people talk bout it too much, it just gets really annoying.