I found this on the 1957 game (interesting note on Nomar at the end)....
In 1957, fans of the Cincinnati Reds stuffed the ballot box and elected 7 Reds players to start in the All-Star Game. They were:
Johnny Temple, 2B Roy McMillan, SS Don Hoak, 3B Ed Bailey, C Frank Robinson, LF Gus Bell, CF Wally Post, RF The only non-Red elected to start for the National League was St. Louis Cardinals' first baseman Stan Musial. While the Reds were known to be a great offensive team with many outstanding position players, most baseball observers agreed that they did not deserve seven starters in the All-Star Game. An investigation showed that over half of the ballots cast came from Cincinnati. The Cincinnati Enquirer had printed up pre-marked ballots and distributed them with the Sunday newspaper to make it easy for Reds fans to vote often. There were even stories of bars in Cincinnati not serving alcohol to customers until they filled out a ballot.
Commissioner Ford Frick decided to appoint Willie Mays of the New York Giants and Hank Aaron of the Milwaukee Braves to substitute for Reds players Gus Bell and Wally Post. In addition, Frick decided to strip the fans of their voting rights. Managers, players, and coaches picked the entire team until 1969, when the vote again returned to the fans.
To guard against further ballot stuffing, since 1969, each team has been given the same number of ballots to hand out. In 1998, that number was roughly 400,000 ballots. Since the dawn of the internet age, online voting has again raised fears of ballot stuffing. In one incident in 1999, Nomar Garciaparra gained over 14,000 votes thanks to an automated computer program. Major League Baseball assures its fans that they have taken precautions to guard against this. Similarly, popular players who are injured often garner many votes despite their inability to play in the game.