[mogwai316]

Hmm, quick math shows that this is actually really bad. If the pleaser pays 6:1, then you need both games to win with prob. > ~38%. Even in the best case, with both games going from +7.5 to +13.5, each games winning prob. goes from 50% to about 29%. Somebody can double-check me on this, but it looks like these bets are even more -EV than I thought.

For 3 teams at 17:1 it works out about the same. You still need each team to have a winning % > 38%, which just isn't going to be possible in the NFL.

It might be worth looking into the numbers for college, where you have more large spreads and the push frequencies for the key numbers are lower.