Sometimes the questions asked here are related to the following three categories ...

Hackers

Yes, yes, I understand there's a fine line between a competent (grey hat) hacker and a sysadmin. But I can't help the feeling that sometimes people come here looking for malicious advice ...

Cheaters

While this is not as prevalent on serverfault as it is on stackoverflow, I've seen a few questions that are obviously homework questions. Students looking to crowd-source their homework.

Lusers

Those few users who feel the need to purposefully circumvent configuration and security controls("Because I need to be more productive!"). And then blame their broken systems on their sysadmins. I've been noticing many questions about proxies, tunneling, and dual-homing systems, where the questioner has no idea about the network equipment being used.

How do you decide to answer suspicious questions?

What ethical responsibilities do we have as a community?

Are there questions that shouldn't be answered?