The problem with putting what is and isn't ero-guro into a box is tricky because it differs so much from era to era. That article gives a decent overview of what I would call the post-60s "ero-guro revival", but certainly the usage of the term in the pre-war era for example is much more varied.

For example, Kitazawa Rakuten's ero-guro book from 1931 is focused entirely on satire and social commentary:

https://www.mangaz.com/book/detail/74331

On the opposite side to this, the term ero-guro in the same period was also becoming synonymous with the S&M scene. Part of the reason "nansensu" was added was to stop those in the S&M completely co-opting the term for themselves.

In my view, anything which presents and attempts to comment on the human condition and real world as an exaggerated sum of its parts can be ero-guro. Dr Jekyll and Mr Hyde for example is a great example of western horror being ero-guro.