Do not rely on it for legal advice.

The Agency’s investigations are complaint driven, so we rely heavily on the public, and our licensees to bring these individuals to our attention.

Or do you rely on a metric or a combination thereof? 

your discovering the B /C issue should have been evident on your personal inspection.. and of course that Is subjective.I like the South Carolina listings they have a little blurb.Is square footage is important to you MEASURE  in other words its what they think it is but don't rely on it and if its important measure it yourself..

Do not rely on it for legal advice.

It's probably not a good idea to rely on a grandfather clause to protect you if your investment strategy depends on it. 

Also, just because you have an agent, don't rely on them to do any of your due diligence.

That said, retail buyers do rely on it to a certain extent. 

I came across a couple properties that I thought were worth a little more of a deep dive but I didn't get much info from the clerk I talked to at the Police Department so I figured I'd reach out to the BP community instead of just relying on Trulia's crime maps.

I definitely could have done proper inspections, and made the mistake of relying on a contractor's appraisal to both identify issues and get a quote, and he then missed things.