Do you think Kid Rock is a good professionally trained aimger?

Johnny cash does not have flawed singing technique, flaw is interpreted by the vast majority, though not defined as:

Localized systematic failure to conform with the flow of ones current observers.

When dealing with persona and persona reception variables within communication.

Johny CAsh, like Ray Charles, had developed a singing style that was described as a "Well tuned chain saw".
If you ever heard any early Ray Charles, he actually sounded a bit like Nat Cole. He worked on his be bop gutteral style,So did Johny Cash, these voices were the result of many years of hard work at sounding that way.

Kid Rock? I liked some of his stuff but a lot of his own work got derivative. Thats why hes doing WWE rasslin now

Yes.
Very much an acquired taste are they not?
I find it depends on the situation, but I can feel comfortable with it in the right frame of mind.