A new poll shows that a month into the job Mayor Mike McGinn has an approval rating of 40 percent. What does this mean?Well, if you’re a McGinn detractor, you probably see it as evidence that people don’t like how the new Mayor seems to be overdrawing on his perceived political capitol. Calling for a seawall replacement without talking to the council first; postponing a planned firing of 200 city workers; and hiring a special advisor who lied about having a Ph.D.If you’re a fan of McGinn’s, however, it’s probably just a reflection that, in an age of cell phones and e-mail, the only people who still answer polls are those with a land line and without the wherewithal to screen their calls.Either way, every poll needs some context. And since this poll is a reflection of a new mayor’s first month in office, I thought looking back at the approval ratings of other Seattle mayors in their first month might provide that.