One thing you have to watch out for in French polls is that Le Pen never polls as well as he finally "performs". People are shy of telling pollsters they intend to vote for him, probably. There is no reason to think he has lost any of his solid base, which is around 16-17%.
I can see your point about Le-Pen, this tendency to lie to the pollster is pretty common. In the US, minority candidates often get a boost in the polls, because no one wants to say they won't vote for a black man. And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
