Yes, this is true! Originally Adam Brody the actor that plays the goofy, quirky, sheek-geek Seth Cohen originally tried for the part of Ryan Atwood - the troubled teen from the other side of the tracks.
Legend has it that Adam Brody (working at Blockbuster at the time) was going to dozens of auditions and when it came time for him to impress the casting directors of The O.C., well he totally bombed.
Adam came in without being prepared what so ever! Josh Schwartz (creator of The O.C.) was instantly not impressed, he kind of hated him really, Josh was even quoted to saying "I never want to see that kid ever again!"
A month later when they still didn't have anyone to play Seth Cohen. The casting director Patrick Rush told Josh Schwartz “I’m telling you, this Adam Brody is very special". So they decided to call Adam Brody back.
This time Adam Brody wowed the casting directors and Josh Schwartz by learning the lines prior to the audition. They saw something very compelling about him and gave him the big fat YES for the role of Seth Cohen. Josh Schwartz later admitted that Adam Brody reminded him a lot of himself, which was perfect because Seth Cohen is loosely based on Josh Schwartz and some of his real life Jewish experiences.
Now take a moment of silence and perhaps a sigh or relief as you thank your lucky stars Adam Brody's on screen nickname wasn't Chino!
For a glimpse of what Adam Brody would have been as a "bad boy" Ryan Atwood catch Season 2 episode 7 "The Family Ties"..In the episode see Seth wears wife beaters, steals cars and acts like a douche bag!