illustration (attribution, if any possible, is at the end of the article)
I've seen many questions recently about finding a 'good' or a 'true' teacher. I've already expressed views (gplus.wallez.name/PUQ2AeReGEM) on this topic earlier, and on one's inescapable responsibility when picking a teacher: there's no warranty on the tin… and there were enough scandals through history to challenge anyone thinking that a particular criterion or another would allow inherent safety.
A response recently given by on the "Buddhism Q&A" community (plus.google.com/u/0/communities/115670914730176750973) was valid in my view: a "real master is [a] real person you go to and really work with".
I think this captures as well as it can the 'essence' of it (and, unsurprisingly, is compatible with multi-faith gplus.wallez.name/4cvsivp1YfJ and with various forms/formats of interaction): whoever makes you question and enquire is a teacher, for a period of time (brief, or long…).
In some buddhist schools, everything (not just sentient beings) has 'buddha-nature': every experience teaches you something about reality!
Now, of course, you're entitled to feel that the Buddhist teachings —or even those from a specific school of Buddhism— offer tools and methods which are more appropriate to help you than stones (gplus.wallez.name/K6NZcWtzScK). Your conditions and circumstances are specific and, yes, a specific tradition might be better suited than another. So you might seek a 'buddhist' teacher…
wrote once a crisp "pros-and-cons", suggesting that why you might not need a teacher, and also why you might (www.alanpeto.com/buddhism/buddhism-teachers).
The various posts I mentioned above (with the Canonical references they point to) already provide many elements to help you pick wisely a teacher. These are guidelines, and… you're still responsible for your choices (and only owning this responsibility will allow you to learn from the experience… and maybe pick a better teacher next time!).
But a few more points may be considered.
…the Blessed One answered [Ananda], saying:
« What more does the community of bhikkhus expect from me, Ananda?
I have set forth the Dhamma without making any distinction of esoteric and exoteric doctrine; there is nothing, Ananda, with regard to the teachings that the Tathāgata holds to the last with the closed fist of a teacher who keeps some things back.
Whosoever may think that it is he who should lead the community of bhikkhus, or that the community depends upon him, it is such a one that would have to give last instructions respecting them. But, Ananda, the Tathāgata has no such idea as that it is he who should lead the community of bhikkhus, or that the community depends upon him. So what instructions should he have to give respecting the community of bhikkhus? »
— Maha-parinibbana sutta (DN 16)
If one enquires the nature of reality and realises (at least partly) the selflessness of it, it is quite normal to doubt one's own ability to understand and/or to teach… And in such context, it makes sense that a student would only start teaching after being encouraged by a teacher [this may explain why paccekabuddhas, or "solitary buddhas," rarely teach, in spite of their complete attainment of the fruit of holy life. Some Theravādins even consider they never teach, however the Jātaka tales say different. The fact is: having Awakened without a teacher, no one encourages them to teach!].
However, this is wholly different from the rather common case of teachers parading the names of who 'authorised' them to teach.
These teachers who cannot live without their 'credentials' (feeling the need to publicise them at every opportunity, the need to aggrandise their self-based legitimacy thanks to the legitimacy of someone else) ostensibly take themselves more seriously than the Buddha did in his last days… which is laughable.
Selflessness is not optional in Buddhism, it's one of the three seals.
When the Buddha explicitly rejects appointing a successor, on the ground that it is not about the person but about the Dharma, any teacher who feels the need to claim authority (on a lineage, on the saṅgha, on some kind of Truth…) has not realised the teachings.
'True' teachers have all been encouraged to teach by their own teacher(s)… but they don't feel the need to 'milk' it: they just start teaching, in all simplicity!
This being said, there are a few signs you can look for:
• "teaching in all simplicity" usually means there will be no pre-requisite to receive teachings [this doesn't mean you should never consider showing your appreciation]. If you ask a question, you're likely to receive an answer. It doesn't "have to" be the case (e.g. if you abuse of the situation and unwisely waste resources, or due to other circumstances), but exceptions are worth enquiring a bit further;
• lineages are defined by the precepts a teacher follows, not by who gave them to the teacher… Lineages are not defined by which sūtras or teachings one studies either. The transmission is by the vinaya (or more generally by precepts, when lay people are concerned). "Ethical life" can be defined by various sets of precepts (and you cannot assume these to match your prejudices: if in doubt, one has to ask which precepts were taken…) but adherence to the chosen "ethical life" is a far stronger indication of lineage than anything else (and humans make mistakes, —even the Buddha had karmic residue after his Enlightenment,— fair enough… but you may still distinguish those who deny any mistake, from those who own theirs);
• teachers are —almost by definition— those who can recognise the realisations of others, so teachers who can only talk of themselves in relation to any 'Truth' (or predecessors and students of themselves (i.e. still themselves, only indirectly)) are likely to be delusional. The Buddha explicitly rejected the idea of individual-based succession! Selflessness is not optional. Teachers worth their salt can happily acknowledge other teachers (and not just from 'their' lineage), because they don't feel the need to own the Dharma and they're able to actually see —for themselves, without recommendation or reference— "who got it".
(See also gplus.wallez.name/DsfHhpr4AR3)