loving nic-names ??
Could speak volumes about a person not wanting to be called an endearing name.
Perhaps ?, generally older people?(undefined) may warm to pet names or endearments *love, darling*etc, just by way of a freindly interaction, instead of a more formal addres of Mr./ Mrs.or a more familiar use of fore-names, John / Mary for instance.
For myself, when working for some-one particularly 1st visits, and untill both parties get to know each other well, I would take the formal approach, ie, Mr. / Mrs.
I never call some-one by their fornames, unless invited;
This I think is the basis of a professional approach,.
Feeling at ease with a particular person, soon gives you an instinct of how that person may / may-not want, or expect to be addressed.
A lot of people in this modern time, can be agressive, and suspicious of the other persons intentions, and maybe of a Narcissistic personality, clearly that person should be treated in a formal manner,as they would object to overfamiliar niceties.
I,as a rule, only use pet names on people I am fond of and comfortable with, and never intentionally patronise any-one.
On the other hand, people can call me whatever they want...
Early in the morning.
Late for dinner