Earlier quoted context omitted.
Help Vampires are users who incessantly ask simple and/or previously-answered questions and provide nothing of value to the community. Over time, they can drive valuable contributors away. http://slash7.com/2006/12/22/vampires/
That post (aside from being overly juvenile) is pure speculation and not backed by any sort of data that would suggest that "help vampires" impact the larger community. It's an extremely condescending and unprofessional term to refer to your less experienced users. It really betrays the core problem with the SO staff. They've gone moderation mad and see the user base as the enemy.
The guy who only needs a single link to the right tutorial is easy to deal with and makes all sides happy.
The guy who asks a question because he didn't even bother to read the 5-page beginner's tutorial (you know because he comes back after 1-2 minutes) where answer somewhere further down... well... after seeing your 50th or 100th of that kind you just want to yell at them.
Others expect you to fix their pastebinned code for them and do not take prose for an answer. They don't want to understand what's going on and what they did wrong, they just want you to do it for them.