Here's another thing to consider when betting money lines.
In the majority of situations, the book only makes money (assuming balanced action) when the dog wins. Say a certain game (or fight) is +600 and -1000. (That spread right there should tell you something.) Now assume player A bets $1000 at +600 to win $6000, and player B bets $10,000 to win $1000 at -1000. If the favorite wins Player A pays player B. But if the dog wins the book collects $10,000 and pays out $6000. Nice racket, huh? Remeber the Tyson Buster Douglas fight? That fight opened at 27-1 and closed at 42-1. Here's a quote from Jimmy Vaccaro who ran the Mirage sports book at the time: VACCARO: "I figured if there's a fight there has to be a number on it. I opened the Buster Douglas/Tyson fight at 27-to-1 and people jumped on Tyson. The first bet I took was for $81,000 to win $3,000. I moved it to 32-to-1 and the next guy bet something like $93,000 to win $3,000. And since we were the only place offering odds, everybody had to come to the Mirage if they wanted to bet." How crazy do you have to be to bet $93,000 to win $3000? I mean you must have an ego the size of North America. He doesn't say what the spread was, but I'm sure it was very wide. You can read the rest of the article about that fight and the Douglas/Hollyfield fight that followed it here.
Tyson/Douglas Fight