How do you say "NO" - RhythmMan, TheKIDD, JW123 qu

Once in a while you have to say "NO" to make your "YES"'s believable.
This may seem like a stupid and naive question, yet I found myself troubled with it.
All the time I plaid in bands I was invited there by friends, or friends of band members. This time is a first time in my life when I call people for auditions. Schedule times and so in search for the "right" people.
Those of you who are pro's (TheKIDD, JW123, J-HALEY, RhythmMan and others) Question to you:
1) How do you say 'NO' to a guy?
2) If you not sure "yes" or "no" because you have other people scheduled, how long to you wait to give an answer?
...This dude reads my ad on craigslist, comes across as he is a virtuoso bassist, sends me a descent enough demo. I arrange meeting and fly to the studio through rush hour traffic. He arrives.
Pawn shop equipment, out of tune, out of key and out of time. Will not take a second to listen to the riff. Can't stay tight with anything even a simple 5 chord progression. And I hope to god no one passes though the hallway in the mean time...
...At last the torment is over and we are outside and I am thinking to myself: "please do not ask me when we rehearse next time".
What would you do? (there is no question of him being a part of a lineup of cause)
In fact any suggestion for hosting an audition would be welcome. I am sure the people who come in will also audition what my partner and I do. I am confident in my ability to play, it is the politics I have problems with. I do not want to f**k this one up.
Share your wisdom, oh experienced ones!
This may seem like a stupid and naive question, yet I found myself troubled with it.
All the time I plaid in bands I was invited there by friends, or friends of band members. This time is a first time in my life when I call people for auditions. Schedule times and so in search for the "right" people.
Those of you who are pro's (TheKIDD, JW123, J-HALEY, RhythmMan and others) Question to you:
1) How do you say 'NO' to a guy?
2) If you not sure "yes" or "no" because you have other people scheduled, how long to you wait to give an answer?
...This dude reads my ad on craigslist, comes across as he is a virtuoso bassist, sends me a descent enough demo. I arrange meeting and fly to the studio through rush hour traffic. He arrives.


...At last the torment is over and we are outside and I am thinking to myself: "please do not ask me when we rehearse next time".
What would you do? (there is no question of him being a part of a lineup of cause)

In fact any suggestion for hosting an audition would be welcome. I am sure the people who come in will also audition what my partner and I do. I am confident in my ability to play, it is the politics I have problems with. I do not want to f**k this one up.
Share your wisdom, oh experienced ones!