If I remember correctly it is crit and %damage amplification (ex: the "devious minds" bonus from t10, or tricks of the trade) that are snapshotted whenyou cast Corruption.
Haste & spellpower values are reapplied each time you refresh corruption via SB/Haunt so no snapshotting
That's what the warlock guide says and I have been able to test it myself on dummy
http://forum.warmane.com/showthread.php?t=380134
It's likely that other afflis make better use of their %damage/crit procs to snapshot those for their corruptions than the original poster does.
Procs/buff to look out for:
-PoS HC trinket (20% crit)
-4t10 proc (10% damage)
-Death's embrace (12% damage)
-tricks of the trade (15% damage)
-crit pot/crit weapon