Something has lighted in my mind this morning.
I will call CQ. Then someone calls me. I quickly respond him/her exactly in this way;
599 NO QSL
If he/she goes away giving me a report, that means he wanted that type of QSO.
If he/she wanted to know more of me, he/she is a ham who enjoys conversational QSOs.
Of course, my response could discourage such a ham. But ther are too many who do only contest style QSOs. I would discourage them not to call me any more. They are too many like white ants eating a wooden house.
I would name it as THE LITMUS TEST FOR CONVERSATIONAL QSO.