You'd only say someones judgement about themselves is unreliable if they will contradict themselves later. But if it is a permanent change, then you are talking to the "new" person who is capable of judging this as well as anyone.
All things are bad if not taken in moderation.
My experience (personal and thus merely anecdotal) on mind altering drugs has been only positive.
My SSRI medication was very welcome when I needed it, and I am very happy they 'altered my mind' and helped through some very dark times.
If I was hit by depression again I would not mind trying a psilocybin based medical regimen.
Like if im suffering pain, I don't want to get drug-induced quasi religious epiphanies from psychedelics. I Just want the pain managed. And what's really annoying about LSD is how it keeps getting promoted as a wonder drug here.
What happens when docs start prescribing it for back pain too?
That's you buddy. Then don't take it. Others who have chronic back pain might be totally fine with this.
And pain killers, at least OTC ones, don't alter someone's psyche. We can, more or less, rely on their judgment that painkillers are helpful. You can't necessarily say the same for mind altering drugs.