Just because certain container types (like skeletons and barrels) are unlikely to contain decent loot, it does not mean that it is not worth checking them. The awesome Smuggler's Ring is on a random unmarked skeleton you can find very early. Since there is a 0.05% chance a skeleton can "drop" a goodie, you will check all of them, especially on a first run. There is a major difference between a container type never or rarely having good stuff. It is just a nasty trick to bloat gameplay times.
I was using the "drunk gnome" just as a hyperbolic example. There are too many items that share the "tiny buff/debuff on a very specific condition" pattern. Some of these can be good on certain builds, but they make for an underwhelming reward in the average case. You very rarely get exciting items, compared to the time you spend opening containers.
Runs often end up all boiling down to the same handful of actually good items every time (Things like Knife of the Undermountain King, Phalar Aluve, the single cloak that gives +1 AC, Melf's First Staff, Caustic Band, Ring of Protection etc).
Except for the Caustic Band, all the others on your list are lost if you fail to pick them up before Act 3.
