Speculative Stock

Hi, In Schweser SS 14 it talks about speculative stocks vs speculative Companies. It goes onto to say that almost ALL of the time, the Spec stocks are OVER priced. Is there a reason for why they are overpriced becasue by definition those types of stocks are highly likely to have low/ negative returns. If investors were rational, then wouldnt it be safe to assume that the security will be corrrectly priced or even underpriced? Not a big issue just thought it might be good to understand why they would be overpriced! Any ideas? Thanks

Willy Wonka Bars… Theres a golden ticket in one of them… Even though they cost 10 cents to make…and stores can sell them for $0.99, people really want that golden ticket…so they are willing to pay $9.99. Golden ticket - wonderful future profits for a company. You pay more for the chance of huge rewards