How Truthful does the MLS have to be?

[Stanley Kong]

This came up because I asked my agent for comps on my current residence. I found out that my neighbour downstairs sold their property and on the listing it listed as 943 sq feet. 

However when I looked it up on my Strata AGM documents I saw that the unit was only in fact 842 sq feet. Is it normal to be off that much?

Also.. on a separate occasion.. I was looking at some properties that were listed as "Fourplex" however when I look into the description it says that it is a Duplex, but the basements (unauthorized) are rented out. And in fact it only has 2 seperate addresses and not 4 separate addresses.

How truthful do these listings actually have to be? 

Does anyone have any experience with listings that are way off? 

Do real estate agents who post these not get scrutinized by the law? 

Is it because they have that little fine print that says "The enclosed information, while deemed to be correct, is not guaranteed." ?