undercover
Some questions:
(1) Why would you send an instantly recognisable college football star to go undercover?
(2) Why was he undercover using his real name? Actually these 2 points may offset each other - no use using a false name if everyone knows you're Johnny Utah anyway!
(3) What exactly was the plan once he'd become accepted by a surf gang? How would he go from that to identifying the ex-presidents?
Don't forget, it was just implausably dumb luck that the first people he met were the people he was looking for....now, if the FBI had some intel that Bodhi and co might be the culprits and then sent Utah to try to infiltrate them, that would have made more sense.
(4) Before the big reveal, their best lead was Latigo Beach. Just staking out the beach and observing the behaviour of Warchild et al would have been enough to make them want to have a closer look. Which begs the question, what was the point of him learning to surf at all? And leads to the most important question:
(5) Why couldn't he just walk around with the surfboard under his arm and act stoned?