What ever Thai said to Isaan people in good or bad way, Isaan people just smile and say yes, yes sir you are right khaaa or khraaab! I can even kiss your ass sir!, very funny right?
I have many Issaan friend in Thailand they looked ashamed to speak their father language (Lao) with me, in particularly when we were in the public area.
I notice that Isaan people even can not step on the shadow of Thai.