Classical psychedelics and dissociative aneshetics are like, polar opposites. Yin and Yang. Yes, they're both sense-distorting drugs that provide interesting psycological effects, but I don't think I'd ever confuse a dissociative with a psychedelic.
Most classical psychs I find are sense amplifiers, they make you more aware of your body and the things in your sensorium. Dissociatives on the other hand, make yo less aware of your body - sometimes to the point you'd swear you're a free-floating ball of conciousness lacking a brain or body at all.
Some people do report dissociation from using classical psychs, but I would expect that to be a psychological response (Fear? Terror? Autistic sensory overload?) and not the drug's fault. If you give mushrooms or LSD to someone who's having an awful time with their life, is knowingly disposed to psychosis/panic/emotional outbursts, and/or posesses generally bad vibes, dissociation could be one possible result. (Other possibilities which are not so nice include legal charges, injury or loss of life.)
Most people who have a positive outlook can manage to handle a trip even if they have something on their mind. Some Spanish-speaking cultures refer to the use of psychedelics as "work", which I find is an accurate description of handling your emotions on a trip. Trips undertaken with the aid of an experienced, perceptive, and empathetic guide/sitter, I would say would be definitely beneficial experiences in the long term. So, you don't need to be a blank smiley face to trip. Just don't drop acid when you attend your best friend's funeral and are still grieving.