Well, even the opposition (at least the sane ones) today admit that Putin's popularity is quite high - much higher than popularity of said opposition. Even in our social networks (including LiveJournal) there are many, many people who honestly believe that Putin is doing a great job. And the silent majority are mostly apathetic, because of "If not Putin, than who?" mentality. There is no reason not to trust these polling figures, as there is no political or social force strong enough to prove them wrong. Some historical parallels (1933-1939, anyone?) are quite scary, to be honest.