He's dated everyone from Jennifer Aniston to Jessica Simpson to Jennifer Love Hewitt, so clearly the man has had sex appeal at some point!

John Mayer was spotted leaving Katsuya in Brentwood last night, and we're not sure what's going on with his hair or shlumpy outfit, but we totally miss his hotness! Remember the stud from the Gap ad back in 2007? Sigh...

John Mayer has completely changed his tune.

The "Waiting on the World to Change" singer, who deleted his Twitter account after receiving some flack for his "offensive" remarks, has ironically written a blog post that expresses his distaste for the overuse of sarcasm.

Mayer expressed:

"If you want to be truly intimidating, if you want to make an impact, if you want to have a strong connection with others, just be sincere. Sarcasm is not an attitude, and it's not a personality trait. It's a style of rhetoric meant to be used occasionally to highlight a larger point. Saying you're a sarcastic person is like saying your favorite cuisine is salt. Sarcasm is easy because you never have to take a stance. And that’s just the problem; It's so noncommittal."

The musician -- who once called former flame Jessica Simpson "sexual napalm" went on to say:

"I don't know when the lines got crossed and it was deemed attractive to be ambiguous and critical. Girls don't like it when guys do it and guys don't like it when girls do it. I live in a city of cool people with the absolute worst PR representatives: themselves."

Mayer concluded with the message: "Be yourself, even if that means being unsure or uneasy. Let someone else put you at ease. Meet them in the middle. Be sincere."

John Mayer revealed in September that he had nodules on his vocal cords. Now, the singer has posted to his blog, revealing to fans that he underwent surgery for the masses of tissue.

He writes:

"I had surgery this [Thursday] afternoon to remove it and am now on complete vocal rest for a month or more. It's been a very long process in waiting to see if time was an alternative to surgery, but even given two weeks' voice rest (along with many other approaches), there was no change for the better."

Mayer was forced to cancel September concerts with Tony Bennett in Los Angeles and an appearance at the iHeartRadio Music Festival in Las Vegas after being diagnosed.

X17 caught up with John Mayer on Saturday in Beverly Hills, only hours after the singer announced he had to cancel concerts and push back his upcoming album due to a throat condition.

Mayer wrote on his blog that he has developed nodules on his vocal cords -- a condition he's been keeping secret for months. The nodules, also called granulomas, can become quite serious.

The singer was scheduled to perform at the iheartradio Music Festival in Las Vegas next week and with Tony Bennett in LA. In addition, his new album, Born and Raised, has been pushed back to a 2012 release instead of this fall. Said Mayer:

"‘Born and Raised’ is complete as far as music recording, song selection, and in some cases mixing, but because of this condition I couldn’t finish singing on several of the tracks."

Mayer says he isn't sure how long he'll be out of commission, but while he's vocally benched, he'll be in New York working on new songs.

Apparently this look is no shtick - John Mayer is channeling Johnny Depp for the long haul.

The singer sported a denim jacket, feather pendant, cobalt scarf, gray jeans and yet another Indiana Jones-like brimmed hat - to dinner with friends at Katsuya in Hollywood Thursday night.

Maybe the boho look is inspiring his next album ... Jack Sparrow is a wonderland?!

Wait -- which John is it??

John Mayer seemed to be taking a page out of Johnny Depp's style guide as he went to dinner at Katsuya in Brentwood on Saturday night. Either that, or he's been watching a lot of Indiana Jones lately.

All he needs is either a snazzy mustache or a whip to complete his look of choice.

John Mayer dined with pals at fav celeb spot Tavern in Brentwood Sunday night. And with that T-shirt and long hair ... he was literally and figuratively one big target.

Of course, Mayer doesn't help himself. At a recent concert at Berklee College, he told the audience that he had quit Twitter. "I was a Twitterholic," the singer said. "I had four million Twitter followers and I was always writing on it ... and it started to make my mind smaller and smaller and smaller and I couldn't write a song anymore."

Twitter! The incredible, brain-shrinking website! Alert the scientific journals! Thank you, Dr. Mayer.

At Tavern, our photogs asked Mayer about the Twittincident. Watch his response below.

John Mayer has fans of all ages ... even senior citizens! Maybe it's the Mr. Roper (from 70's show Three's Company) attire?

While arriving at LAX, the 33-year-old crooner showed off his very unique fashion sense ... plaid coat, green cargos and a funky leaf necklace. What happened to the clean cut John we love so much? Guess that style went away with Jennifer Aniston.

Find out what event John will be hosting in New York ... after the jump.