Somewhere in Italy, the main criterium is to be in the right place at the right moment...other recommended criteria are (in loose order): 1) to be young enoug but not too much, 2) to be old enough but not too much, 3) to be able to attract funds, regardless of the value of your research, 4) to be part of a "magical circle" (i.e.: the "academic" stronger group in your institution, 5) to lead on relevant research project (unfortunately, the quality of your research is usually judged by the aforemensioned "magic circle"), 6) to have enough experience, usually the one you may obtain by leading on the research which are part of the position you are competing for (terribly complex, isn't it?). I'm afraid such criteria are becoming widely used...
Thank you very much for your reply. It sounds very difficult and unclear to become a professor in the "somewhere in Italy". But normally, like in my country, there are some rules or guidance for that. Like in my country too, there are several rules that were very subjective, and sometimes the peer/reviewer said them as a "convention among them". Another unfair rules are the minimum criteria. It depends on the institution.
We are discussing about creating an international organization of lecturers and researchers for us. I think you would like to be a member or organizer.