I therefore don't know what marketers think about this. But it would seem that there are basic things to know about when dealing with customers/buyers. This isn't going to be a long lesson in how to to that - i just wanted to say a few words about customer type, which I think we all could do with knowing about.
There are two kinds of buyers: The genuine ones and the scammers.
So you need two methods only: Be nice or be nasty.
Both can be a bit of an art, and the better your use of English the more easily you will be able to understand what you are dealing with - and to be able to respond in the most appropriate way. I would say that if this isn't you then look at professional style messages from your inbox - take examples from there and modify as and when.
Rule number one is be nice to all - to begin with. Do not assume anything. Sometimes customers get it wrong and need to be handled very gently. Most just need a replacement or refund.
Refunds: Do it! if a customer is unhappy for any reason whatsoever provide compensation - partial refunds can be a good option.
Be quick: Always answer fast to any queries. Within 24 hours is long. 12 is better. They may buy elsewhere if it's a product enquiry.
Rule number two is a fact: genuine customers CAN and WILL be satisfied - especially if you are friendly and personal. Scammers will NEVER accept anything other than keeping the goods and your money.
Deal firmly with these people. If it means bad feedback or reviews you will have to handle it. You can't let scammers win. If that is out of your hands then it's out of your hands. Just do your best and refuse to give ground. Any hint by a dissatisfied customer that they think returning the item before getting a refund isn't correct indicates potential trouble.
Bearing all that in mind you may occasionally encounter a different kind of customer: one that is angry at life in general. They may give premature feedback or other unfair comment. They'll probably regret being unreasonable but in the meantime the damage has been done. There's little that a seller can do to prevent this kind of thing.
So be as quick to respond as you can, be as nice as possible to everyone - but know when someone is trying to take advantage of the system.