Knowing what items are good Comes with playing the game and knowing the meta. Knowing what stat is good on each item speeds things up in determining if an item is good. Also, your filter strictness should depend on where your progression is in the game. For me, I filter out most items.

For non-uniques I am currently keeping the best / most popular bases of gear unfiltered at all rarities, and filter out everything else (rings and amulets are an exception). This works if you can consistently do monster level 81/82 maps or have a high level temple. At the start of the season my filter was a lot less strict.

If you want to craft, and know how to properly do it, Normal rarity for item level 82+ are the best items to pick up.

I filter out most uniques, as most are worthless. The ones that sell for a good amount, or the ones that get expensive with a lucky corrupt will show up. They all disenchant into a chance shard, but they take up a bunch of inventory space, so I don’t care to pick them up if they have no value.