Benjamin Franklin said, "Guests, like fish, begin to smell after three days."

Well, today is Day Four of the GOP Convention. And for some Minnesotans, there is an unpleasant odor in the air - especially in the view of those swept up in Monday's arrests in St. Paul through no fault of their own.

"I didn't think it was possible in the USA that police would just 'round up the usual suspects' and pick out the guilty ones later," said Steve Wells, a Minneapolis attorney. "I'm outraged."

Wells' 17-year-old-son Daniel was arrested Monday while trying to get to the Labor Day concert on Harriet Island. He was released from jail about 4 a.m., and made it to the first day of school at Southwest High. Another 17-year-old from Eden Prairie, also arrested while trying to get to the concert, had his photo flashed around the world, identifying him as one of the anarchists attempting to disrupt the convention. But in the picture, he is wearing all white with a red cap; the actual anarchists are in black.

A Minnesota Nice myth has popped up that none of the 300 arrested are from here. Message: Don't worry about them. They're outsiders who deserved it.

Many did. They wanted to provoke police to show the strong-arm tactics they believe rule the nation. The cops behaved professionally, and with restraint, for most of the day. But in some cases, journalists, onlookers and everyone else was fair game. Even one Republican got arrested.

Sam Welna, 22, is a faithful Republican who has a degree in political science from the U of M and has worked for Republican state Sen. David Hann. He was arrested Monday on a bike path along Shepard Road while watching the protests and attempting, unsuccessfully, to obey what he said were contradictory police orders. He was still in jail at 8 p.m. last night, waiting to be released after pleading not guilty to unlawful assembly.

"We support the efforts of police to prevent personal injury and property damage," his parents, Mark and Cathy, wrote to me. "We are however appalled at the actions that have resulted in our son's loss of freedom for three days."

Welna "was caught up in what we call a 'sweep,' " says attorney Phil Villaume, who helped train protest observers how to avoid arrest. "He was in the wrong place at the wrong time. But the police should use more discretion before they make these wholesale kinds of arrests. They seem to have been trying to be intimidating."

The Welnas think the cops may have thought Sam was from out of town because he was wearing a University of Kansas T-shirt. Then again, they point out, "most attending the Republican convention this week are from out of town."

Watch out, Republican delegates.

Meanwhile, in the strangely surreal city that resembles St. Paul but has lost much of that town's fabled charm, the GOP's pistol-packin' mama, Sarah Palin, rocked the house last night at the Xcel Energy Center. Tonight, it is John McCain's turn. Then, our ripening guests will leave -- delegates, protesters, out-of-town cops, media.

Maybe that will clear the air. • 612-673-4400