The non-ironic what? The non-ironic "free, white, and twenty-one" -- that guy wasn't kidding. Idiomatic, yes. Ironic, no. The usage that is neither idiomatic nor ironic, I don't think is broadly available. There's probably someone somewhere in, I don't know, Montana or who knows what who thinks we ought to get back to the good ol' days, but no, I don't think it's widespread.

The non-ironic "mighty white" -- yes, I think it's broadly available enough that the ironic usage you speak of didn't actually occur to me until you mentioned it, even when whozit and I were talking about the actually disparaging use of "white" in this morning's thread.

Non-ironic "Mexican carwash" etc. -- I couldn't tell you what I think about "Mexican carwash" and "French leave"; I expect they're normally used wryly, but haven't they always been? (Also "Irish beauty".) "Chinese fire drill" has always been silly. "Russian roulette" and "Indian giver" are both absolutely unironic, I'm afraid.