You can start from here and you may found self-rating scales where staff over-rate their own capability. This is a real bias. Also the moral problems that emerge in diffirent settings. I attach papers where these problem is discussed.

doi: 10.1037/a0033045.. 2013 Jun;50(2):158-66.Psychotherapy (Chic)

Trainee psychotherapists' development in self-rated professional qualities in training

Inga Dennhag 1, Helene Ybrandt

I am not aware of a valid and reliable scale. Here is what I know. Many who counsel have struggled with their own addiction struggles so they can overidentify. In society at large, addicts are perceived as exhibiting very low social value.

I am aware, after 50 years in the clinical field that countertransference of clinicians who do not abuse are more compassionate and they manage any negative countertransference more aptly.

I attach a few of my clinical articles just for future reference.

Rich

I found this pdf (short 2015 review) that discusses stigma assessment (both self-stigma and public stigma). There is a table at the end that provides a run down of a few attempts at this in the past that might prove useful. Good luck :)