transactions: Request a refund for a Bitcoin order would be the best way to transform your Bitcoin into national currency?

Leave Be an online store that accepts Bitcoin as a payment system, along with payments in USD.

In the context of a refund, the user gets USD.

Now, Alice has, say, some bitcoins, and she wants to convert them into USD. To avoid conversion rates, she has the idea of to buy something with Bitcoin's and request a refund / cancel the order, once the successful transfer has been made.

Is there a conversion fee in this context? I know that when buying / selling BTC, there are some fees (the same for currency conversions in general). Are the omitted in the described context?

I know it may not be very ethical to do this, but I wonder if this is possible and ends up with more USD in Alice's hands, compared to the traditional BTC → USD conversions (using some random internet service).

This, obviously, can be extended to the fact that if the Bitcoin falls in the next few weeks, Alice can get the refund in the dollar value she paid when she placed the order. If BTC goes up, she keeps the product.