How often do you find international vehicles made in a different country and not in their home country?
You need to clarify what it is you're asking here. Your post's title asks about quality but your question seems to be about whether cars made in a different country have been seen here. If you mean imported cars they're obviously an everyday sight and have been for decades. Or do you mean grey-market or privately imported cars that are not normally sold here?
In the United States you can bring in a non-compliant car only if it is at least 25 years old. (In Canada I believe it is 15 years.) If you bring in a newer car and it is discovered it will be confiscated and crushed.
I've seen a few privately imported vehicles at car shows but that's about it.

To clarify: how often do you see cars that weren’t sold here due to safety or emissions rules?
Not very often at a reasonable price.