TAMPA — There are 15,000 credentialed journalists here covering a meticulously choreographed Republican National Convention. So what’s a reporter looking for a new angle to do?

Not to worry. These events are magnets for swarms of activists, advocates, and hawkers of every stripe. Trying to piggyback on a quadrennial political pageant, they create a grand bazaar of American sideshows, subplots, and causes.