Specs can be used as a general starting point ASSUMING all other things are equal. In other words, just because a $100 set of 10 watt powered computer speakers specs say it's flat and goes down to 35 hz does not mean it will sound anything like a $600 pair of bookshelves that have the exact same specs. Specs won't tell you how the speakers sound to a human.

Your ears...and more importantly common sense...should be the final deciding factor.