Intrade simply follows the latest polling & conventional wisdom. Subject to market manipulation.
Intrade bid and ask volumes are very low as well - a few hundred dollars are enough to swing some markets from 90% to 10% probability.
With a two account set up, you can swing markets for only a nickel on the dollar to swap money between accounts - buyer and seller being the same person.
That’s why the Patriot Act /US gov got all over them for money laundering issues a few years back.