I imagine most seasoned professionals placed on a PIP will probably already have a reasonable guess if it's a BS posture or honest attempt to fix a problem. If not from the get go, definitely by the first 1:1.
I guess, it doesn't really matter what the company calls this process or how it's presented, only how it is conducted. If you even mildly agree with the reasons presented for it, and you get positive feedback soon, it may work out, otherwise it most surely won't, regardless of the honesty behind it.