Offering money brings you people who are interested in the -money- and not the art of acting. There are exceptions, but in general I don't offer anything but food and drink. If the person is passionate about the art, he/she will be there. If you haven't found out by this time, you will
I saved a ton of time by NOT offering money and it's a good filter to keep things simple for me.
P38 is right about the money. If they're more interested in money than acting, they will never become great actors.
Sorry, but as someone who has handled all aspects of several productions (casting, directing, producing) and who acts, I disagree with this line of thinking as an absolute rule of thumb.
There is nothing that guarantees if someone is interested in receiving money for their skilled work that they will not become good at it. You're also not guaranteeing anything special by not offering money, other than eliminating yourself from ever hiring some really good actors with the confidence to require payment, no matter how small, for their craft.
I know that, from a practical, monetary point of view, there are times when you cannot afford to pay for an actor but you still have a need/desire to shoot something. But to say you're getting more passionate or better people by not offering money...? Maybe, but passion doesn't always replace talent or ability. Which is why so many no-budget projects never get anywhere and don't make any money.
I know when I'm looking for work and going through ads, I no longer open or read the free gigs anymore. I did my time working for free. Unless it's a friend's project, or something that is brought to me that is really interesting, I won't work for free any more. I learned as a comedian, and it applies to actors - at some point, you have to say "no" to free gigs, or people will expect you to work free, forever.
If you want to make a living in a creative field, you have to get paid for your work. ANY kind of pay is better than offering nothing. You increase your talent pool, and the number of people with skill who apply, if you offer even $25 a day. As the pay goes up, you have more better and better people to choose from - offer $100 a day for a film project, and you'll get resumes from really experienced, talented actors fighting for the job.
Forget passionate, so-so actors willing to work for free - get hungry, strong actors who already have fully-developed skills and pay them slightly better than a minimum-wage employee gets for a day, and watch the quality of your projects skyrocket.
gelder