Privacy exemption and non-personal entities

I’ve increasingly found that requests are denied on PII grounds when they don’t have anything to do with individuals—several years ago I sought OSHA complaints by category (eg sexual, religious discrimination) and sought the entity name that was cited (eg BigCo Inc) and was denied because that would reveal PII data, but I’m unclear about corporations and rights to privacy in FOIA.

I also know agencies widely interpret this on their own. Related to this questions is being denied identifiable records about complaints versus violations— more and more entities will claim trade secrets or something similar to prevent their name associated with anything unfounded, but often times nefarious actors can be uncovered by having a number of unsubstantiated complaints, rather than waiting years until government determines a complaint is valid.

Anybody have any relevant experience, best/good practices, pre-emptive techniques that work with specific agencies or at large?