NOTE: this ticket should probably be split in future for simplicity.
Cases which are already split:
The bug
Certain faces of blocks are still rendered even in conditions which would make them absolutely impossible to see outside of spectator mode.
This ticket only lists blocks which use the standard block rendering method and not blocks such as chests which render differently in a manner similar to entities.
Affects the following blocks, as seen in Spectator mode through an opaque solid block:
Bottom faces:
Brewing stands
Iron bars
Glass panes (fix provided in MC-122927)
Four turtle eggs (fix provided in MC-135986)
Chorus flowers
Side faces:
Anvils
Bell (attachment:floor)
Chorus flowers
Top faces:
Anvil
Glass panes
Iron bars
Chorus flowers
Related issues
is duplicated by
relates to
testing discovered
Attachments
Comments


Most of these blocks will now cull appropriately.
Doors don't cull, as all doors support transparent textures.
Shulker boxes won't cull either.

So all are fixed but shulker boxes and doors (they can still be fixed witthout removing the transparancy ability)?

This fix breaks chairs in custom resource packs. Would be nice, if you could choose whether blocks cull or not in resource pack.
[media]
That’d be a feature request.

Here's a full list for bottom faces I've found that are not included here, along with tickets that can be merged (as duplicates):

Grindstone bottom face fixed in 18w45a

Currently in the process of fixing many cases. Resulting resource pack with fixes will be attached to this bug report.

I have since created a resource pack which adds cullface for all blocks affected, with the exception of blocks which already have fixes provided and blocks which do not use cullface at all. Will attach shortly.

The fix texture pack has been attached.

Texture pack outdated as of 18w50a; uses old bell model. Will update eventually.

Fixed for some blocks in 19w02a

Numerous cases fixed as of 19w03a

Even more fixes as of 19w03a: only remaining blocks appear to be four turtle eggs, glass panes, brewing stands, normal and redstone torches, iron bars, dragon eggs, bells (against a wall), anvils (against a wall), and beacons. The other blocks which use tile entity rendering I'd consider a separate issue.

Can you please strike out entries in the lists which you think are fixed? And in case you know when a certain item has been fixed, you might want to put a Fixed in 08w15a next to it.
Verified remaining issues and updated ticket

(19w11b) Found some more:
Top faces:
Potted Cactus
Bottom faces:
The unpowered redstone torch-like parts on the Repeater and the Comparator, as well as the Repeater's 'lock'. Forget cullfacing, these simply shouldn't have bottom faces at all
Walls (if two walls are connected, and have another two connected walls on top of them, the bottom of the wall posts on top will not cullface)

Still in 19w13a

Still in 1.14 Pre-Release 1

Still in 1.14 pre-5

Still in 1.14 Release

Still in 1.14.1 Release

They just need "cullface", but for some blocks like iron bars, adding cullface data will cause other bugs.

Currently in the process of creating a resource pack which should fix these among other model and texture bugs.

Can confirm for 1.16 pre release 5

still happens in 20w27a

Hello, I also made a model optimization resource pack and thought it might be useful here...
Also, while making it I found a few extra things that I fixed in the pack:
- Fence Gates don't cull the top part when a block is above them
- The Fence Gate model (Closed) took 8 cubes when it could've used only 5 (By joining each gate)
- The Fence Gate UV was visually inconsistent when it opened and closed (This isn't an optimization thing but it mildly annoyed me so I fixed that too)
- Parts of Repeaters, Comparators, Tripwire Hooks, Fence Gates, Beacons, and Dragon Eggs had faces that would never be visible anywhere except in Spectator Mode (Like, they were inside other parts of the model)
- Dragon Eggs have an unnecessary cube (Kind of like Fence Gates)
- Flower Pots have a few unnecessary cubes as well
[media]<- Just reuploaded it because I put it in the .zip wrong
P.S. I did not add culling to Glass Panes and Iron Bars because that causes other issues

I believe this also applies to glow lichen in 21w06a
[media]
Also affects the bottom faces of lightning rods.
Can confirm in 21w16a.

Can confirm in 1.17 Release Candidate 1.

Affects 1.17.
Can confirm in 1.17.1.
Can confirm in 1.18.1.
Can confirm in 1.18.2.
Can confirm in 1.19 and 22w24a.
Can confirm in 1.19.2.

Can confirm in 1.19.3

All torches now don't render their underside as of 24w33a.

still an issue just turning off Ambient Occlusion fixes though.