I have a list of non paying clients up on my wall.  I just counted 32 names, 90% of which are out of town companies.  It tooks 10 years to make this list but it comes in handy as every few months a magical order appears from one of them.  I wait 2 days and send it back with a note.  That usually keeps them away for 6+ months until they try again.  Guess they think we are stupid or forgetful.

You did not pay us 2 years ago, we know you wont pay us now.  They are always suprised when we turn their work down.

As for loyalty, I used to have guys come behind me in the courthouse and hit redial on the phone to try to find my clients.  I know because I would finish talking to my client, hang up and secretly dial my cell phone.  Poof, 5 minutes later one of those "new" guys are calling me asking the name of my company.  That was the old days though when I used the phone in the court house.

I have more stories, but you dont want to hear all that.  Just give good service and pricing and you will be fine.  If the client is new, be suspicious until they build a good payment record.  If you do good work, you will stay busy and get paid.  Problem is, many guys think they do good work and dont realize how much stuff they miss.  They complain becuase they cant get anything done because their phone wont stop ringing with questions and requests for additional work.  That is just one hint that they suck.  The other is the idiotic questions they ask, even though they have 5+ years experience.  Crazy.