As an aside, I'd always assumed that you only got so many "flags" per minute or whatever, but I've had a half-dozen where my flag killed it dead (which makes it all rather fun), so maybe I was mistaken?
Not all HN users are "flag equal", if you consistently flag spam then sooner or later a mod will notice this (as many flags get reviewed) and you'll get upsized to "super flagger" - unlimited flagging power with one flag == death.
You then get more scrutiny, start "petty flagging" (flagging a fellow legit HN user out of spite because <insert no good reason>) and you'll be demoted to the rank and file.
If you email HN and ask they'll often happily tell you if you've been tweaked in some manner or another.
