What is the method for students to evaluate qualifications and accept a person as their teacher?
It is always said in India (Buddhists and Hindus alike) that, When the disciple is ready the Guru (Teacher) arrives. The trick is that you start your search to Nibbana in all dedication and sincerity, rest of the events unfold.
There is no way a student can evaluate a teacher. I mean how on earth I can know anything about, say a 'Geshe' degree or if you are an academic or an Arhant?
Altough what can be done is you can do some background check before you commit, but if there is a shady teacher who is not yet exposed in that case nothing can be done.
But there is another thing, that is called as Innocense. Knowing lot of spiritual con-men I can attest that those trying to acheive the ability to fly in the air end up with the con-men and those with a sincere search for Nibbana will end up with right teacher. The cunning end up at feet of cunning. It takes masive deal of Karma on one's part to arrive at true teacher of Dhamma (not to be confused with saaying that victime are responsible for their troubles).
How can a person that knows very little of the Buddha's teaching evaluate if a person is a Buddha?
No, you cannot eveluate a Buddha, you just evaluate your own truthfulness and your own intentions.
In other words, "appo dipo bhava", be a light (island) into yourself.
"Monks, be islands unto yourselves, be your own refuge, having no other; let the Dhamma be an island and a refuge to you, having no other.
-- Attadiipaa Sutta: An Island to Oneself
Also of interest is the Kalama sutta.
So in this case, Kalamas, don't go by reports, by legends, by traditions, by scripture, by logical deduction, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, 'This contemplative is our teacher.'
When the Buddha says that you can't go by logical deduction, inference, or analogies, he's saying that you can't always trust your sense of reason. When he says that you can't go by agreement through pondering views (i.e., what seems to fit in with what you already believe) or by probability, he's saying that you can't always trust your common sense. And of course, you can't always trust teachers, scriptures, or traditions. So where can you place your trust? You have to put things to the test in your own thoughts, words, and deeds, to see what actually leads to suffering and what leads to its end.