Sure; total blinding is an issue with many drugs (however active placebos which can make you feel dizzy/sedated/whatever can help); opiods/fentanyl/etc sometime

Sure; total blinding is an issue with many drugs (however active placebos which can make you feel dizzy/sedated/whatever can help); opiods/fentanyl/etc sometimes have to make do with imperfect blinding. The fact remains that the psychedelic state is so distinct from normal consciousness that the challenge is qualitatively different.