I recently had two divergent experiences in guest relations, both occurring on Park Avenue, though not on the same day. They offer textbook examples of how to — and how not to — treat customers.

The first incident happened when I stopped in for a midweek visit to the newish Trattoria Toscana, a small restaurant on the lower end of the boulevard. I was by myself, and the young man who greeted me when I walked in barely disguised his disappointment that I was alone and would lower the check average.

He suggested I might want to sit at the bar, a suggestion I hear often when I dine alone. For some reason, restaurant hosts assume solo diners don’t want to be seen eating a meal by themselves. I know that some people feel self-conscious as a single diner, especially when the restaurant is filled with couples. I’ve never had a problem with it, maybe because I’m usually “working” when I’m dining, so my mind is on the task at hand and I couldn’t care less what the people around me are thinking. And while I do enjoy eating at a bar simply for the experience it can provide, most times I prefer to be seated at a table

(Occasionally, I’ve had servers or managers come up to me after I’ve been seated at a table and offer me a newspaper or even a book to keep me occupied. It’s an ingenuous gesture, but the underlying assumption is that a solo diner must be bored and would rather be occupied with some task. I prefer to watch what’s going on a round me, thanks.)

I certainly wanted a table at Toscana. A quick glance at the bar, which overlooks a rather unattractive cook area, told me it was not going to be a fun place to sit. So after I told him I would rather not sit at the bar, the young man pointed to a table for two at the front of the restaurant, a table that looked rather cramped between two other small (and occupied) tables, and one at which the owner of the restaurant was currently seated while he conversed with a couple at the next table.

Farther back in the restaurant were two four-tops, both unoccupied. I asked the young man if I couldn’t sit at one of those. He said, “Those are my only four-tops.” I glanced at my watch and asked if he was expecting more people at that hour, which was already after 8:30.

At first he just shrugged, but then grudgingly said he would reset a table for one. But I was already over it. “Never mind,” I said as I turned to leave. Why would I want to stay in a restaurant that didn’t want me? I’d rather give my money to someone who is happy to see me.

I’ll happily give my money to the folks at Barnie’s Coffee & Tea Co., which offered the other lesson in customer relations. Ironically, they ended up giving me my money back in order to show how much they valued my business.

It was a Saturday afternoon and I was strolling the avenue. As I approached Barnie’s I thought a cup of coffee sounded good. I entered the store and ordered a small cup of coffee and paid the young woman at the counter.

She handed me an empty cup. I guess it had been a while since I had been to a Barnie’s and I was unaware that the customers are expected to pour their own coffee. Or pump their own coffee — it’s contained in large dispensing pots, the kind with a vacuum that releases the liquid when you press a button.

This is the way they do it at Panera, and I’m not a fan — self-service is less service. But I took my empty cup and went over to the coffee pots and pressed the button.

Nothing, just a little gasp of air indicating the pot was empty.

So I asked one of the two women behind the counter if they had a full pot. One of them, with a big smile on her face, said she would fill my cup from behind the counter, and “it will be the freshest cup of coffee you’ve ever had.”

This I took to mean that she would have to brew another pot. I said I really didn’t want to wait for that and asked if I could just get my money back.

The other young woman, at the cash register and also with a gracious smile, said she would be happy to refund the money — and she would still pour the coffee for me. There was no wait at all. I had my $1.73 in one hand and a piping hot cup of coffee in the other in no time. And both women thanked my for coming in and wished me a good day.

What struck me about the incident was that neither woman hesitated even a moment. They knew immediately — and intuitively — what to do to make the situation better, to make a chagrined customer happy.

Perhaps Barnie’s could send them down the block to give a few pointers to the staff at Trattoria Toscana — and a few other places around town.