Aren't all poll results skewed these days? Any polling experts out there? (details)?

Most polls are conducted by phone these days, right? But most cell phones are unlisted numbers, right? So that means most all people who are polled or surveyed are using land-line phones. Yet I'm guessing that 50% of this nation uses a cell phone only. And; I'm thinking that demographically speaking, most of these cell phone-only folks are younger people, say under the age of 40. That would further suggest that those with land-lines are a more aged population, and thus (perhaps?) more conservative. I realize I'm generalizing, but am I wrong to conclude that 'younger' persons views are not truly reflected in national polls anymore?