For what it is worth, here is my 2 cents:
I know at DomainSite.com we give refunds on registrations all the time if the domain is still within the grace period. Usually because of user error (registering a misspelled domain, didn't know what they were ordering, etc). The registry does not refund registration fees after the grace period. As a result, registrars cannot really refund fees either. We also give refunds for other services if customers are unhappy and if there is no other way to make them happy. There is no use in keeping an unhappy customer. If we can't please a customer, and some people just cannot be pleased, I would rather see them go elsewhere. However, even when losing money on a customer, we generally strive to fix whatever problem it is they are having.
Margins are so thin in the domain industry. If you only gross 50 cents or a dollar on a domain, and you spend more than a few minutes dealing with a customer about that domain, you just lost money. You have to strike a balance somewhere. That balance is often struck by offering a lower quality of customer service or by not offering refunds. I can understand this position to a point but you have to support your customers and if you can't you don't really belong offering a service. You have to at least try.
My guess is that most registrars want to have happy customers. I think the problem is in the volume. There are registrars that are one man operations that probably cannot provide a level of service their customers desire. Then there are the registrars that have lots of support staff but also have tens of thousands of customers. They are almost in the same position as the one man registrar in that they probably cannot provide a level of support that all of their customers desire. The level of support that is desired by customers always seems to be greater than the level of support a registrar can provide and still sell domain names at a price that is competitive in the marketplace. Then of course you have the behemoths with operating expenses and exec salaries that are so high they have to charge 30+ dollars for a domain and still can't afford to provide decent support.
I think you could probably find tales of good and bad service for all mainstream registrars, just like any other industry.