[Vrul]

Here is a version that throttles the amount of processing:

local FaithfulDeleteList = {
    [     1 ] = true,   -- <unknown>
    [     9 ] = true,   -- <unknown>
    [  2455 ] = true,   -- Minor Mana Potion
    [  6289 ] = true,   -- Raw Longjaw Mud Snapper
    [  6308 ] = true,   -- Raw Bristle Whisker Catfish
    [  6309 ] = true,   -- 17 Pound Catfish
    [ 17057 ] = true    -- Shiny Fish Scales
}

local frame = CreateFrame("Frame")
frame:Hide()

frame:SetScript("OnEvent", frame.Show)
frame:RegisterEvent("BAG_UPDATE")

frame:SetScript("OnUpdate", function(self)
    self:Hide()
    for bag = 0, NUM_BAG_SLOTS do
        for slot = 1, GetContainerNumSlots(bag) do
            local itemID = GetContainerItemID(bag, slot)
            if itemID and FaithfulDeleteList[itemID] then
                print(("Item found: %s [bag: %s, slot: %s]"):format(itemID, bag, slot))
            end
        end
    end
end)