I could not agree more. All my working life I seem to have been given the difficult or problem customers. Sure it was always a bit uncomfortable at first, but as you said when I worked out they had been stuffed around by others in the company I worked for, it was pretty easy to fix and deal with. I only just finish working for one after 17 years and that was only because he retired.
There's a great deal of satisfaction to winning over a customer everyone else sees as difficult and creating a great relationship; I believe it's important to make the initial approach run the first meeting without preconceived ideas in mind and let things go from there; It's also wise to use ears and moth in a 70/30 percent proportion weighted towards the ears as over-talking isn't a good thing.
There's many elements to relationships, business or personal, and the same ones (generally) apply to both.
I had a great day today, the meeting was a good one and the drive and languishing around in that coastal town paid for by my organisation? What's not to like huh? 😉