Certainly there is scriptural material on how to assess the level of realization of one's guru. However, there is a Catch 22. To know for certain how realized someone else is requires being advanced oneself. That puts the candidate for diksha in somewhat of a predicament. They can either attempt to make their own judgement about a guru they are considering taking shelter of or rely upon the recommendation of others. In the former case, they must first know enough about the established criteria to make an intelligent evaluation, whereas in the latter case they need to know enough about the persons who are vouching for the prospective guru (in other words the substantiality of the guru's good reputation).
The other issue is the limited number of individuals that may just be very realized and the total number of candidates for initiation. Considering that the GV community in India numbers in the millions, that poses a logistics problem. It would be physically impossible for all of them to be initiated by a highly realized sAdhu. So, it would make more sense to first evaluate a prospective guru on the basis of outward behavior, which is clearly observable, as long as a candidate is able to spend a sufficient amount of time with the prospective guru. And that could be a logistics problem as well for the vast majority of candidates. So then what to do? I think one solution is to have some standards board in the community that would serve the purpose of certifying gurus as having the minimum qualifications. That way a candidate could rely upon such credentials to guide them in their decision whether or not to take diksha from any prospective guru.
Any ideas on this?