Mine is soil. I've got a graduate degree in soil science.
The most popular opinion that is wrong is all of the common ones. Soil science takes 5 science disciplines ( bio, physics, Chem, plant nutrition, and soil development) and rolls them all into one.
Not all tillage is bad
Not all amendments are good or work
There is just such a big gap in common knowledge when it comes to this topic and a lot of 'experts'
If you plan to sue it as a garden get it tested. There can be metals and stuff you don't want being taken up by your veggies.
Most natural soils are pretty good. Limitations are highly site dependent. Some have heavy textures, and poor drainage as a result. Some lack nutrients. It depends.
For nutrient poor soils add organic matter but make sure they have C:N ratios below 25:1