Don't rely on the teacher, rely on the teachings.
So here the teacher is seen as an elder. Somebody we respect because she has more knowledge and experience than we do.
Next, in the mahayana, the teacher is referred to as a kalyanamitra -- a virtuous companion or spiritual friend.
Then later in the vajrayana, we develop what is called "pure vision". As a tool or a method of achieving that, we train in seeing the guru as a perfect buddha.
So we ask ourselves, how can this work? If I visualize I have a love affair with a famous movie star, will that lead to me actually achieving that result?
The difference is that we are not pretending. We learn in the teachings on emptiness, for example in the madhyamika, that the true nature of all things is emptiness. In the teachings on buddha nature, like the uttaratantra, we learn that we all have buddha nature. So even though we use a "fake" method of visualizing, it works because all we really do is remove our own obscurations. We simply remove the mud that covers the golden statue--we don't need to create the golden statue, it was always there.
So we try to view the teacher as a buddha at the time of the path. At the time of establishing the view, we should certainly investigate, probe, examine... Who is this man? Is he trustworthy? Does he have the qualities that are required and so on. This is also a very important aspect. Gaining genuine understanding turns what might have been mere blind faith into genuine confidence. This confidence will not be shattered if one day the guru does something strange that we might not like or that challenges our pre_conceptions...