A friend on this forum asked this question today - wouldn't using a glove teach the bird that biting doesn't work and he should just give up? You know, that is (basically) exactly the very first question I asked on a parrot training forum (BirdClick) hosted by Melinda Johnson when I got my first parrot. I got the same answer from her and several other professional (positive reinforcement) bird trainers. There are several people who could perhaps answer better than I, but this is my blog so here goes.
The current thinking on gloves (from trainers like Melinda Johnson and Barbara Heidenreich) that I follow is not to use gloves and not to cause a bite under any circumstances if it can be avoided without endangering the bird.
The thinking is that teaching the bird that biting does not make the hand go away conditions helplessness. The only tools the bird has for making the hand go away in most cases are: 1) move away from the hand; 2) threaten to bite; or 3) bite. If you take away all of those options, the bird has no control or influence over his environment in that situation and you put him in a situation where he cannot flee from what he fears. It amounts to flooding - you lock him in a room with something that terrifies him and make him shut down his "emotions" till he gives up.
There are a lot of parrot trainers that "teach" the birds not to bite in exactly that way - it sounds like a good idea: show him biting doesn't get you what you want. This is a punishment tactic - there is nothing that the bird can do to remove the stimulus; all he can do is shutdown, not knowing what he did to deserve it.
I don't want to teach the bird to tollerate me - I want to build trust by letting the bird see how I will act around him. I want him to like me. I want to build a relationship. That doesn't have to take a long time - sometimes you just like someone right off the bat; but in the case of mistrusting animals, it can take slow movements and small successes.
The way I avoid a bite is: I offer my hand to the bird - if he backs way, I retreat; if he lifts his foot, I let him step on; if he moves toward me (and I trust him), I let him move in to be petted. The key to everything appears to be an ability to read body language. [When I offer a treat to a biter, I put the treat in a small ceramic bowl and let him take it from there, not from my hand.]
In the interest of full disclosure, my experience is with a small number of birds (all re-homed) over a few months time; the pros could do better - read their books for a better explanation.