The definitive guide would be the documentation. Every VI that takes an error in either has the "This VI provides standard error I/O functionality" statement or specifies what happens when an error is supplied. I always document my VIs in a similar manner, usually something like "this VI operates regardless of supplied error state" if not standard, or more specific when need be.
I agree with you and NI's practice of having release and destroy VIs always operate.
Over the last few years I've also started backing off from always having error I/O. Simple VIs which are incapable of generating errors don't have error cluster I/O. I'm looking at you accessor VIs (for the most part).
mje's post in How should "Error In" affect code execution? was marked as the answer