For laypeople, how can one discern if someone offering or describing himself as a medium is in fact truly in contact with those forces or possesses that ability?  Is there a means or mechanism to make that assessment or is it mainly a matter of luck?  I've seen folks who professed to be mediums who were obviously faking and I've seen those who honestly seemed honest, but how can one tell?

Such a good question!  Seeking a medium for yourself is a matter of trial and error.  When you just know that you are compatible there will be a feeling of comfort in the compatibility.  Those are the regular instincts that make us comfortable with other people.  Its in the water - so to speak.  

If we remember there is a psychic/medium for everyone - perhaps it isn't so much  frauds as they just don't resonate with either yourself or your needs.  I recently read a line in a book that keeps me in that balance - it said that for every psychic their is a client and vice versa.  We never know what will resonate with one and not another.

I deffo agree with you spirittalk.  On the other hand, just like shopping for a doctor, dentist, etc., there should be no rule with the person that you can't interview" so to speak.  You can ask how long they've been doing it, or what there most important experience was, or which form of divination they most like to deal with.  While I wouldn't probably ask a million questions, I think anyone honest would not mind you doing this.   Also, if you've then been read by this person a couple or few times, you will definetly know how accurate they are.  hope this helps

An honest and sincere medium does not mind the 'interview' process.  After all, there are so few ways to know about another, without some interogation.

This reminded me of the television show, Phenomenon. Did you see the other night's showing?