I have some actual experience of this. I had worked out a "card game" character creation system a long time ago where all scores started at 8, non-face cards added their value to one of 2 scores associated with their suit, and face cards added a total of 6 to 8 points to multiple abilities. Jokers are "wild", and can duplicate any card in the deck. A card could not be assigned to a score if it would take it over 18, so only an exact +4 bonus could bring a 14 to an 18. Each player got 5 cards. Most of the time, we got characters with an average score of 14, which was high but more or less what I was shooting for.
One fine day, one of my players got a 10, three 8's, a King that added +2 to four scores, and a Joker. The yield was 5 18's and a 10 (the Joker was set to represent a 10, of course). He did it in front of me and one other player (I was playing it to create an NPC's stats, since the card game method spreads the stats out best if played by 3-4 players). I shuffled the deck and dealt the cards myself.
This started quite a discussion among my players and me, and some felt uncomfortable with such an ubermensch in the party and others were fine with it since he's a friend anyway. The player himself was a little miffed at the idea of me nerfing his character. Finally, I decided to tell the player to knock two of the 18's down to 14's and take a bonus feat to partially make up the difference. I feel it was an imperfect solution but not too terribly unfair. He still got to play an awfully good character!
That was our last random character generation. After that, I had them pick their own scores so that their stat bonuses added up to 10 before racial mods, then add 1 to three scores to make them odd.