Those don't exist. There are too many free variables. Some get much closer than others (for instance via formal verification), but all specs are by necessity a model of reality, not the full reality itself.

Nobody actually has any trouble knowing what a bug is. Like, this is just a non-issue, I've never in my career spent a non-negligible amount of time debating with anybody whether something is or isn't a bug. We discuss whether fixing bugs have worthwhile return on investment, and we discuss the relative priority between fixing bugs and doing other things, but this meta-debate about "well technically it complies with this spec so is it even a bug, really?" just never comes up. We all know what bugs are.