I think a better course of action is to deliver high quality work the first time. Yes, a money back guarantee can be beneficial to lead generation, however, it also opens the door for you being put in a position where you do a lot of work, and then the buyer decides that they want their money back just because they didn’t like the work.
The thing is, you did the work. You should get paid for that work. Why waste all that time, when the buyer can just walk away with your work for free? Stand your ground; work with the buyer to meet their needs, but have limits too. Don’t give in to every buyer, just because you want to please them. Please them with good work, but know when to say no, too.
The same goes for revisions. Never, ever, ever give your work away for free via “unlimited revisions”. That’s a horrible gig choice. Once again, you’re setting yourself up to be taken advantage of. Set limits, do no more than one or two revisions, and then cut them off. Good work does not require revisions. Focus on pleasing your buyers with your first delivery.
You’re doing basic work for $5. You’re in this to make a profit. Figure out what that $5 is worth to you, your time and income goals, and then stick with it. Never, ever, EVER give your work away for free. Limits are your friend. Limits are also good business.