There have been a couple of TED talks that I have seen that come near my area of research and expertise. There was a bit of a cringe factor to it, as I had the impression that the speaker was over-simplifying and over-selling.
My guess is that this is the common feeling for anyone very familiar with the material of a TED talk. However, it does spread ideas and make them available to others that would not have otherwise encountered them. There is incredible good in that.