Even what is show quality to one judge might not be to another.
When I think of a chin as show quality, that I have not yet shown, I think of an animal produced out of lines that have been shown and produced me offspring that have been shown so I have an idea of what the animals should be. Anyone who calls a kit show quality should not be taken serious because you can't really evaluate the animal.
I think like anything this term should be looked at by who is using it. If a sanctioned judge tells me they have a 6 month old show quality animal, I'm going to believe them over a back yard pet store breeder who tries to tell me the same thing. In the end it's about the breeders experience and if you think they are competent enough to judge if an animal is "show quality", which to me by the way means no less than a 2nd place, and most likely a 1st or better when judged against it's peers in similar condition. Today's first place might be tomorrow's 3rd, and yesterday's 3rd place might be today's Grand Show.
Jags, I had to read that several times because my eyes weren't working and I just wasn't seeing a difference in wording, lol.
Basically there is no yes or no answer, it's not the same as is this a white chin or a beige chin, and it's a know your seller deal usually.