Well, the example given was just one side of the story (the costs) but not the benefits. If you're thinking right in this case you shouldn't be misled, you should just ask "Then why is it so freakin' common?"

In a less convenient example, if someone tells you about a few studies that support conclusion x (cherry picked out of the larger body of studies that support !x) then that could be harmful if you trust the guy to be an unbiased selector, but in general you should be suspicious of how the studies were selected.

Sure, it's a bit too strong to say you can never be harmed at all if you are at least half sane, but if you're that worried about being misled by truth, you probably have some underlying problems to deal with.

No-one said it did.

And I didn't say anyone said it did.