Here is what my thought:

Let spam = spammer’s posting in A’s Note comment

Let spam1 = spammer’s posting in B’s Note comment

Let spam2 = spammer’s posting C’s Note comment

If spam=spam1: give him waiting time before commenting in B’s

If spam and/or spam1=spam2: give him more waiting time before commenting in C’s

If spam=/=spam1 but being reported by someone, then give waiting time to commenting and posting Note.