Sure, I'll Work For Free

Because someone will ask.  Lots of people will ask.  "I can't afford to pay you for it, but can you do this for me?" It comes with the territory of being an artist.

At this point, I have a few standardized responses I can just pull out.

My standard answer #1:
I'm happy to do it at no charge.
First priority, though, is paying gigs who paid extra for a rush job.
Next are the regular paying gigs.
Then I have the stuff that I create with the intention of selling later, and doing the marketing for my own sales.
Then there's some on spec stuff where I've actually got a contract guaranteeing me a percentage.
Then there's stuff that I do for a couple charities that I get to claim as a tax write off.
Then there's my own projects I'm working on.
Then there's *possibly* some other on spec stuff, prioritized by the time investment to probability of success ratio.
As soon as I'm done with that, I'm happy to get to your thing- Probably sometime next November, if I don't get any other paying work between now and then.
"But we really needed to have it by next week."
No problem- Rush rates are on my website.

Standard Answer #2:
I will play for fun, but I can't work for free.
If you want me to jump up on stage and jam a few tunes, that's fun for me- I'll try to remember to bring my guitar if I make it that day.
If you want me to commit to a day out of my schedule, deal with contracts, compose a set list, learn new material, rehearse, do promotion, pack up my equipment, drive there, unload, set up, put on a good show whether or not I feel like it, pack down, load out, and drive all the way home- That's WORK, and I get paid for that.

Standard Answer #3:
This isn't so much an answer, so much as a response.  I have an Exposure Contract.  If I'm asked to play for the "exposure", I send it to them.
In simple terms, it says that I agree to do the gig at no charge, on the assumption that it will lead directly towards $X in merchandise sales, and/or $Y in other paying gigs.
And obviously, if that doesn't happen within 60 days, then the booker of the original show agrees to make up the difference.
With interest.
And penalties.
And service charges.
EXHORBITANT interest and penalties.
Exorbitant to a degree that pimps and payday loan agents would be ashamed to even suggest.
I'll put the gig on my schedule as soon as the contract is signed (notarized) and returned via FedEx.