King Yao likes to punish lazy sportsbooks and blog about it. I followed his lead found a nice little value while shopping for Super Bowl prop lines just now.
Lots of books have a line on the number of different Patriots to score in the Super Bowl. A common line is something like under 3.5 players at odds of +240.
One book, however, copied the bet incorrectly. They offered +240 on "under 3.5 different Pats players to score TOUCHDOWNS".
Obviously, this is a massive difference. It's like buying a full player for free, since Stephen Gostkowski no longer counts (unless the Pats run an LSU-style fake FG). It could be even better than that, since a two-point conversion is no good either. In fact, this bet can only be -EV if nearly five different Pats are expected to score touchdowns in the Super Bowl, and they're not even projected to score that many points.