Adventures in Roommate Searching

A situation that pretty much everyone can relate to from some point in their lives: Finding a roommate.
The only people I believe that are spared from this..."adventure"... are those who are financially able to live on their own right away after leaving their parent's keep (koodos), or those who never leave their parent's keep.
I was careful enough with my money when i was younger in order to fit into the former, and my parents made sure i would never, ever want to live with them for the rest of my life. So as i realized my college era was ending, i found a roommate and moved out. It was a pleasant six months, with an underlying stress that steadily grew until it exploded and I was forced to look for another roommate.
I put up an ad on craigslist and roommates.com and considering my complex is amazing, queries started pouring in. I forced myself to meet with anyone who fit my three main criteria: Female, Non smoker, financially able to afford the place.
So far i have been able to classify them into four categories:

1) The students: these are the ones who are pulling part time jobs and taking classes or are running solely on student loans and somehow have deluded themselves that they can afford to live with me.

These include:
The 19 year old who didn't know what utilities were much less that they were extra over rent,
The one who showed up 3 hours late and expected me to say yes because she was so awesome,
The ones who asked me if i was 420 friendly (i adamantly am not and turned their names over to the police department),
And the one who brought her bum ass boyfriend with her asking if he could essentially live with us (overnight guests are one thing, this was another)

2) The Not Impressed: The ones who walk through the door and you can visibly watch their faces fall, then they sit and half heartedly get to know you for some odd reason. Then they get up and leave and don't have the decency to tell you they're not interested.

These include:
the 28 year old who decided that she would rather live on her own
the snob...there's no other way to describe her manerisms
and the one who told me yes and then the next day told me about a much better apartment she found for 100$ more

3) The Robots: The ones who come and are as stiff as a board acting like they are in a job interview with donald trump, sit precariously on the edge of the couch and deliver pre-memorized, full fledged, complete sentence, answers to something as simple as "what are your hobbies". They are unable to carry a conversation unless it is a question - answer form.

These include:
the 'afraid to sit on anything' girl
the 'terrified 18 year old'
the 'all but silent' one who stared at me waiting for the next question.
and 'one who couldn't STOP selling herself' to me about why this appartment would be perfect for her.

4) The Potentials: These are the ones whom after speaking with them, I wanted them to move in. However in 3 out of 4 instances, they ended up saying no to me for various reasons:

one got a surprise engagement
one's boyfriend put an offer on a house and she figured she would be living with him more than at the apartment
the one whom i can only describe as fung shui, incense burning, mandala fan whom i later found out was a smoker and then said no to
and the most recent who has a very well behaved dog and i get along great with.

I have two more people to meet with tomorrow. I've had a stressful February and I'm done. I fully intend to make a decision by Sunday and be done with it all. I'm ready to know the answer to what will happen as of March 1 and just get it over with.