How do you assess whether an existing customization violates Clean Core principles?

A structured assessment typically starts with SAP's own tooling — the ABAP Test Cockpit and the SAP Readiness Check — which can automatically flag custom code that accesses SAP standard objects directly, uses deprecated statements, or relies on non-released APIs, giving a quantifiable inventory rather than relying purely on manual code review.

flowchart TD
    A[Run ABAP Test Cockpit / Readiness Check] --> B[Inventory of custom objects flagged by risk level]
    B --> C{Uses only released APIs/extension points?}
    C -->|Yes| D[Clean - low remediation priority]
    C -->|No| E[Not clean - prioritize for remediation]

From that inventory, custom objects are typically triaged by both technical severity (how deeply it touches unreleased internals) and business criticality (how central that customization is to actual operations), producing a prioritized remediation backlog rather than treating "clean up everything" as a single undifferentiated task — a genuinely large legacy landscape might have thousands of custom objects, and not all deserve equal urgency.