Poison damage charms - what builds do need them?

I saw some trades where people are buying/selling small charms with just poison damage.
(and never saw people buying/selling charms with just cold/fire/lightning damage)

From what I know/read, flat poison damage in itens does not worth on a typical attack build.
(and never saw a guide recommending them for any build...)

Is there some specific build that can benefit from this flat poison damage?
(or am I wrong about poison damage charms, and many builds should use them? )

Poison charms (especially small) are sometimes used in PVP. Only you need to stack a lot of it hence the 451 small charm is valuable. Can be useful say when facing ES sorc as poison goes through the shield etc.

If you find the above charm sell it and be happy.

Unsure if they are used in regular builds, someone else may be able to assist on that matter.

What M1ck said + on some off-meta builds like

Dagger Necro, Poison Bowsin or Poison Bowazon/Javazon. I wonder if you could make some weird like double Grief/Plague (or combo) poison Barb as well or something like that... But mostly and mainly for PvP.

Would like to buy cold/fire/lightning damage sc if anyone have them