Imagine no further. Here is the approach I take, and will continue to take. Never would I try to publically demean, shame or humiliate the person with an unaccredited doctorate, so I would not say to someone what you've suggested above. I simply do not/would not use the title "Dr" in my dialogue with them or address them using that moniker, plain and simple. If that person is brazen enough to pursue the issue and demands a reason, then yes, I would share my concerns over unaccredited degrees. It isn't about an "in-your-face" attitude toward unaccredited degree holders as that isn't my personality; however, I can not bring myself to address someone as "Dr" when the credential has not been earned via given norms of academic protocol.