"Pukey green" is a great descriptor.
We've been around long enough to know that "red" is bad or failing. "Green" is good, or passing. That permeates our builds, our tests, our status reports - it's everywhere.
"Pukey green" is great for that precise reason: it's green, so it must be good. But it's pukey, which sounds bad. This is the verbal equivalent of a shrug.
I'd use "pukey green" to describe something that just doesn't feel right, even though so far it looks okay. On the outside, it's working fine, but there's something I can't yet put my finger on that makes me not trust it.
"Pukey green" items are the ones that you can't say why you shouldn't ship them, but you just know you're going to get a lot of customers complaining about it later.
Thanks, good Mr. Hammond, for making my day, and giving me a really vivid way to describe that "yes, but..." feeling.