The weird thing is, often if you ignore the bile and just respond with polite technical questions (i.e., get to the bottom of the bug), these people engage in classic bully behavior and suddenly become all sweetness and light.  It's like they beat on you, then when you show no signs of noticing, they decide you're some kind of invulnerable statue and start playing nice.  I had this (off-list) exchange with a user recently.  Watch the dramatic change of tone in his second mail:

   >> [...]
   >>
   >> Thank you for the worthless link.
   >>
   >> You could have just said, "I think the merge tracking is on by
   >> default with the 'svn merge' command."  or "you need to specify
   >> the -foo flag to enable it" instead you confused me more.
   >>
   >> This experience has given me insight as to the level of support I
   >> can experience by going with subversion.  A bunch of parrots trying
   >> to teach me to fish.  Unless your goal is to make people adverse
   >> to using the product, please in the future take a moment to help
   >> rather than act in a condescending manner.
   >>
   >> Have a nice day.
   >>
   >> --[name omitted]
   > 
   > I thought that blog entry pointed to CLI documentation, but it points
   > to another graphical client -- my mistake.
   > 
   > On the command line, generally the -g flag enables merge-tracking, but
   > there is not yet any thorough documentation of the feature, sorry.
   > You're welcome to help write that documentation, if you wish (see
   > svnbook.red-bean.com, for example).  Much of what gets done here gets
   > done by people pitching in where there's a need.
   > 
   > -Karl
   
   Thank you, knowing there's nothing is better than searching
   endlessly. :)
   
   I can try to see what I can whip up.
   
   I've done docs (and [...] code) for [famous OSS project], so I hope I can be
   of help once I get over the intial hurdles.
   
   Is there a general area I can look for understanding how -g works?
   
   This is actually linked to somewhere off that initial link you gave
   me and seems to help some:
   
   [...link omitted...]
   
   thanks!

   --[name omitted]

By the way, the "condescending manner" he was referring to in his first mail was not, IMHO, condescending, it was just a statement that it would help if he'd given more detail in his original, public post.

I'd be surprised if he actually contributes, but you never know.  He does appear to be a real contributor on the other project he mentioned.