A: Top posters
Q: What is most annoying in Usenet?

A bit longer:

> So that's why you say not to top-post! 
>> It is helpful to say, in effect, "you said X; my answer is Y."
>> If you edit the message to which you are replying to quote just
>> the "X" part, then give your answer "Y", everything is pretty
>> clear even if earlier versions are missing.  Your own article
>> will stand by itself.  This convention has been developed over
>> more than two decades, and it works well; longtime USENET readers
>> seem to prefer it on average. 
>>> Can you put it all together for me now? 
>>>> There are a few problems with this theory.  USENET messages have
>>>> a tendency to get lost or mangled or even simply forgotten, so in
>>>> fact, one often *does* have to page down to read the entire quoted
>>>> text, then page back up to find the reply.  Moreover, if the
>>>> quoted text is long -- as it often is -- it can be difficult even
>>>> to tell which part you MEANT to reply to. 
>>>>> What's so bad about that?  Especially since you can stop reading
>>>>> as soon as you have seen the part you already saw! 
>>>>>> Since top-posters only have to write their reply, then include
>>>>>> the original message, they tend not to edit down the original
>>>>>> message. 
>>>>>>> Well, I have an answer to that, but OK: what is the second? 
>>>>>>>> It makes conversations come out upside down.  The TV game
>>>>>>>> show "Jeopardy" is one of the few places the answer should
>>>>>>>> appear before the question. 
>>>>>>>>> What is the first? 
>>>>>>>>>> I can give you two reasons. 
>>>>>>>>>>> Why is this bad? 
>>>>>>>>>>>> This is the practice of writing your reply, then
>>>>>>>>>>>> including the original message below (often the whole
>>>>>>>>>>>> thing, instead of just the part you are replying to). 
>>>>>>>>>>>>> What do you mean "top-post"? 
>>>>>>>>>>>>>> Please do not "top-post".

Copied from some dark corner of the USENET.