What does Macbeth's reaction to the witches reveal about his character in Shakespeare's Macbeth?

Banquo's reaction to the weird sisters in Act 1, sc. 3,
is, at first, disdain in their appearance (ll. 40-50).  Macbeth seems almost angry when
he tells them to speak, if they can.  After the three greetings that witches give to
Macbeth, Macbeth seems stunned, "Good sir, why do you start and seem to fear / Things
that do sound so fair?" (ll.58-59).  Banquo goes on to tell the three witches that if
they can give predictions to Macbeth, then why not let him know his future.  He tells
the witches that he does not fear them, nor does he court their favor.  Right before the
witches vanish, Macbeth demands them tell him more.  He is quite serious at this point. 
Banquo, when the witches vanish, asks whether or not they really saw the witches or if
they just imagined what they saw.  When he repeats the prophecies to Macbeth, it seems
he is doing so bemusement - with a "yeah, sure" attitude.  When Ross delivers the news
that Macbeth has, indeed, been named the Thane of Cawdor, Macbeth is clearly awestruck
and immediately hopes that the prophecy that he would become king will come true (ll.
148-150).  The thought fills him with fear, though, too (ll. 155-159).  Banquo suggests,
however, that the witches haven't done a good deed with their prophecies and that they
aren't harbingers of good news, but rather, they are devils trying to win over Macbeth's
soul by giving him a minor prediction that has come true and hoping to lead him astray
with the bigger prophecy of becoming king (ll. 142-146).  Banquo, of course, was right
to be suspicious of the witches' motives and Macbeth was gullible, allowing his ambition
to guide him.  Macbeth's reaction shows his ambition when he says, "Two truths are told,
/ As happy prologues to the swelling act / Of the imperial theme," (ll. 148-150). 
Macbeth wants to believe the witches because of the good possible outcome for
him.