How do Arcane Sight and Greater Arcane Sight interact with illusions?
If you recognize the illusion magic, do you automatically disbelieve illusions that require a will save? Similar to true seeing?
Arcane sight has the line, You know the location and power of all magical auras within your sight. Does this allow you to pinpoint an invisible foe? What level of concealment would such a foe have?
An invisible foe would still have full, 50% concealment. Pinpointing their square won't be an issue, however.
Whether or not you automatically disbelieve the illusions or not is something you should ask your GM, as it isn't clearly covered in the rules.
I suggest you check out this thread which is aimed at getting questions like this answered in an official manner.
Please add your question and hit the FAQ button on my original post.