Once I had booked a hotel in Hong Kong for a week, pretty expensive, and I finally couldn't go. But this was in an especially hectic moment (personally and professionally) so I missed the full refund deadline for cancellation. It was obviously my fault, as the deadline had been clear from the beginning, so I just cancelled without refund (or maybe with partial refund, I don't remember) and moved on.
The next day, and without having asked, I got an email from Booking saying that they would negotiate with the hotel to see if they could give me a full refund anyway. A day after that, I got the refund. It was a substantial amount of money so I'm quite grateful to whomever did that at Booking.
On the other hand, I hate their pricing practices, e.g. presumably because I am a relatively frequent customer, the website often offers me worse prices than my wife who almost never used it. Also different prices on mobile and PC, etc.