President Barack Obama, with his daughters Malia Obama and Sasha Obama, waves to a gathered crowd as they leave the Bunch of Grapes book store. (Carolyn Kaster/AP)

Along with his job approval rating, the president’s “book bump” is not as strong as it once was.

In his annual visit to the Bunch of Grapes book store on Martha’s Vineyard, Obama purchased two books for his summer reading list: “Rodin’s Debutante” and “The Bayou Trilogy.”

Back in 2009, Obama’s book purchases saw a subsequent spike in book sales. According to Politico, he bumped "The Way Home" from No. 33,349 to No. 328.

Compare that to the 2011 sale. “The Bayou Trilogy” went from No. 17,005 on Friday to No. 308 on Monday. He had to move the dial only half the amount, and yet the end result is about the same. By Tuesday, it had fallen back to 1,020 in the bestsellers rank.

Of course, perhaps we should tweak the old saying a bit: Never judge a president by his book sales.

If you do want to buy “The Bayou Trilogy,” here's what the Post’s Book World had to say about it:

Under the Bright Lights

This powerfully written mystery introduces Rene Shade, a detective in a town that seems to be riddled with corruption. The plot centers on Shade's attempt to track down the killer of a city councilman and of the owner of a porn theater, and a trail that seems to involve the mayor, a construction kingpin and bad men from the Cajun mob. Woodrell can plot a novel with the best of them, keeping the action going and the reader's interest level high. The real pleasure of this novel, however, is in the taut descriptions, deftly sketched characters and the life-like relationships.

Muscle for the Wing

The Wing in the title of the novel is a prison gang led by one Emile Jadick, who has come to the town of St. Bruno to take over the gangs that run the already corrupt bayou town. Accompanying him are Dean Pugh and Cecil Byrne, two fellow ex-cons with a taste for the seamier things life has to offer, and Wanda Bone Bouvier, one-time waitress and full-time sweet thing. Enter police detective Rene Shade, on assignment to locate the members of the Wing. As Shade continues his investigation, he must ask himself who he is working for:the city? or the gang bosses who really run things?

The Ones You Do

“The Ones You Do” is [Woodrell’s] third novel set in the fictional bayou town of St. Bruno. Here John X. Shade threatens to renew acquaintances with a previous wife, three grown sons and an old poker pal whose spouse he cheerfully seduced many years ago.

The gifted Woodrell is often praised as a "writer's writer," which can amount to a curse these days. It's another way of saying he's too original to be mainstream. Maybe that's so, but his writing sure goes down smooth and easy. "The Ones You Do" is great fun. The dialogue is dazzling and hilariously ironic, reminiscent of Thomas McGuane. And the characters are slippery and warped just as they are in true life, if you're hanging out at the right joints. Woodrell's white-trash philosophers might see things in a peculiar way, but they see clearly.

Here's one of John X. Shade's sons, watching his father in a bar and thinking about time's brutal march: "The old man had been tanned by the light of too many beer signs, and it just goes to show that you can't live on three decks of Chesterfields and a fifth of bourbon a day without starting to drift far too ... wide in the turns."