disclosure and barring service, DBS, enhanced security clearance, enhanced DBS

I’ve been thinking a lot recently about disclosure, security clearance and enhanced DBS checks.
I’ve had a significant amount of experience lecturing in offender learning establishments and discussing the probability or even possibility of ex offenders gaining employment after release.
The main thing that always arose from discussions is the misunderstanding of when a conviction is ‘spent’ and what to declare to employers.
My answer is ‘absolutely everything”.
Honesty is the best policy always and it gives employers a better understanding of the conviction and shows more integrity from the candidate.
There are, of course some crimes that are never spent, and some ex offenders may never be suitable for certain jobs.

As an employer how would you make the decision to fill that vacancy? Do you have your suitability criteria and all the guidance?
What if 2 candidates of equal caliber interviewed and one had a police caution? Which one do you employ?
If you’d like to have foresight rather than hindsight I’d like to hear from you.