When asked I've always said "I don't do commission work". That's letting them know even if I did make them one I expected them to pay for it.
Did do a quilt for DIL, she paid for the fabrics, supplies and LA quilting but it hung heavy on my mind until I finished it. . She loved it but she's not a picky person. I've learned from others who have been asked to make quilts that when they made the quilt the person requesting it wasn't pleased, colors didn't look like they thought, it's not big enough or too big, etc., etc. they just kept nit picking as if they paid for it.