Hi Selena,
To answer your questions:
1. Yes. It is possible. I have been involved in such assessments for quite sometime (e.g., for a national award on Sustainability) and many times I could see the gap between what is written as "Code of conduct" or "Business Values" and the practice on ground.
2. Audit need not be based on a "Standard" (like ISO); as you know an audit is a structured process with Client, Auditee, Auditor, Audit Criteria etc., defined properly and the process steps as per agreed procedures - the agreement on the audit objective and methodology is normally made between the Client and the auditor. An assessment is slightly different; it is an evaluation of a thing, process, person, etc. (example: EIA, Assessment for an Award etc.). An assessor (for example, a Sustainability Assessor) has to be a person of knowledge in various dimensions which can be used to evaluate the subject in question. An assessor may also use auditing techniques to carry out the assessment. In simple terms, it is like a teacher evaluating a student - the teacher does not base his evaluation (assessment) of the student by his/her examination marks alone (which is similar to audit findings), but also by his interaction with him/her inside and outside the class.
3. Experienced Professional: The analogy given above is handy here; a teacher has to be an experienced person in the subject matter to evaluate the student. Similarly an experienced professional (in the subject, for example, in Sustainability) is required to evaluate (assess) an organization, individual, products, processes etc., for their values, eco-efficiency, compliance etc. There are quite a few Professional Organizations which help individuals to grow professionally in specific fields.
4. My experience is that any organization that has faced a few audits will be able to meet the audit criteria by "providing" "evidence". But in an assessment, the assessor, goes beyond the "audit" process and "audit criteria". His "Opinion" (assessment) matters in the final outcome of the assessment. (for example, when we carried out an assessment for an award, even though the desk top evaluation indicated to a stong Sustainability bias in the organization, the interview with the CEO indicated that his understanding of the subject was hollow - we didn't want him to know the nitty-gritties, but he should be aware of borad understanding of the subject. We evaluated this organization "poor" under Leadership)
Hope the above gives you some idea of what I meant by a combination of audits and assessments.
With kind regards,
Ramakrishnan