In america I think they mainly use DSM IV but the international statistical classification of diseases is ICD-10, available online here:
http://apps.who.int/clas...ns/apps/icd/icd10online/(schizophrenia and other mental disorders are F20-F29).
I think it depends on the psychiatrist to some extent, but I personally doubt most of us would be labelled as schizophrenic considering how functional we are and how we dont exhibit certain key features of schizophrenia (such as auditory hallucinations which comment one's actions, and insertion/ withdrawal of thoughts into/from one's mind).
Though I dont doubt some people would be seen as having delusional or acute psychotic disorders, and while often those would be wrong/biased diagnosis, I wouldnt say that in all cases they would be completely mistaken, as there have been some quite serious psychiatric issues displayed by some people IMHO... Or more likely some would be diagnosed wuth having some kind of "mental and behavioural disorders due to psychoactive substance use" (f10-f19)
Do note though, that they specifically say that schizophrenia should not be diagnosed in the state of drug intoxication or withdrawal, and that in acute psychotic disorders they say specifically that stressful situations a couple of weeks before should rule out this diagnosis
Also another important thing to say is that the statistical classifications are just that: classifications. I think the problem in bad practice is not necessarily related to the classification, but rather to how one would follow once they have a diagnosis. Do you think Rick Strassman or Charles Grob would treat a person the same way as would Dr Conservative Alopathic Prick ? Definitely not.. I have met good doctors and bad ones, and the way they treat a patient is completely different, even if the diagnosis is the same. For example one could give anti-psychotics forever and forget about it (or increase if symptoms dont go away), another could even give some medicine in accute cases but could also have complementary therapy, would support artistic expressions, would search for support of family and friends in the treatment, etc. Also this doctor would have mid-long term strategic plans and would ultimately try to reduce as much as possible the medication in a level that the patient can try to deal with his issues and yet be functional and not hurt himself or others, hopefully quitting medication altogether.
I am very critical of a lot of psychiatric practices too, make no mistake, but I dont have a naive view as many do... I know there is a lot of "killing of symptoms and not treating deep issues", but thats not with all of psychiatry and psychiatrists.
I think its easy to criticize psychiatry and calling it this or that, but have you ever had experience with different schizophrenic or people with other serious mental conditions? Psychiatric patients are not all just "shamans being medicated and losing their powers" or something of the sort. Of course there might be some instances where people are diagnosed as schizophrenic but they are actually going through some psycho-spiritual crisis that isnt necessarily pathological. But there's also people that are suffering greatly and are really having mental difficulties, hurting themselves and others, and psychiatric treatment might be the only way to give them a bit more tranquility to work on their issues and continue life. Im not a psychiatrist, im a psychologist in the educational area so I dont have much direct experience with this kind of mental health but I did do some internship in my studies in a psychiatric hospital and I saw first hand how complex it is.
I believe conservative Big-Pharma-backed mainstream psychiatry does need to go through a big paradigm change and that they have actually caused a lot of damage and numbed a lot of people instead of helping them, but I also think some psychiatrists have seriously saved many lives and were able to help lost souls finding a humane path and a happy(er..) existence.