Yes! Yes! Yes! I have experienced all of these!
Can you knit a baby layette for me by next week? Most of the time they offer to pay but are horrified when I point out that even using cheap K-mart yarn it's going to cost more than if they bought something. This is because I wear self-knit sweaters and people assume I do that to save money. I actually do it because they last and look impressive at work. Most of my sweaters (with good yarn bought on sale) cost in the $100-$200 range. Why? Because when it takes me 50-100 hours to knit something, I'm not exactly keen on wearing it out in a year. I have a few sweaters made of good yarn and I can expect to wear them 20-30 times per year for ten years. Even if I paid myself $10 per hour, I can wear a sweater that is worth around four figures. Yes, I do make much, much, much more than that professionally. No, I can't compete with some poor person in Bangladesh who gets supplies in bulk and barely makes enough to feed themselves.
The other thing is beginner sewers who borrow my sewing machine "for a few days." Sure, I don't have time to sew any more (other than mend and take in clothes to fit my odd-shaped boy). But I don't want it to disappear for three months.
I've even done the "writing" thing. I used to love writing groups and then got tired of people who said, "I have an idea for a story." Because most of the time it was a girl-meets-boy "except, I want the heroine to be smart and sassy instead of passive." Wait, you want me to write
Pride and Prejudice for you? You do know it's out of copyright?
That's not to say I'd never do a favor for someone. I had a friend whose daughter was expecting a child with a fatal heart disease. I made a free white blanket for him and was very humbled that she thought my work was good enough to wrap him in. (He was buried in it.) You can bet I dropped everything to make it. She gave me a nice gift certificate to a restaurant and offered to baby sit for my kids. The truth was that with the gift and the baby-sitting, she still ended up paying me $5 an hour. But I felt like it we were trading nice gestures as friends and it wasn't me being paid.
Bethalize, I don't mind using my mad cheesecake baking skills. (If I have the time.) I love to eat my cheesecake and I'd like to have someone ELSE eat the rest.

(Sheesh, this thread makes me sound totally vain like I can do anything! I just have a few skills that I have been working on for 30 years of my life. I still can't make soup to save my life. It always ends up funny.)