By Zachary Fagenson
MIAMI, Dec 6 (Reuters) - The acrid smell of spray paint fills the air in Miami's once-blighted Wynwood neighborhood where graffiti artists from all over the world have descended, covering walls - sometimes invited, sometimes not - with eye-popping murals from traditional graffiti lettering to themed designs.
"This is the place to be relevant, where your work can be in the public eye," said a 35-year-old, New York City-based artist called Mast.
He and others flooded the streets donning gas masks, part of an estimated 70,000 art enthusiasts who have converged on the city during its annual contemporary "Art Week," centered around an event called the Art Basel Miami Beach fair.
Wynwood, located just north of downtown Miami, is filled with hip-looking crowds posing for pictures in front of murals that adorn more than a dozen square blocks, creating a unique outdoor museum.
"This place is amazing, it's where you can come to see all of the artists you see online, in magazines," said Haroldo Paranhos, 27, visiting from Brazil. "You never have so many big walls like this all together."
The week draws globe-trotting street artists like Shepard Fairey, famed for his 2008 blue-and-red portrait of Barack Obama captioned "Hope." Better-known artists like Fairey paint for free but are sponsored with free paint, a wall and a team of assistants to undertake big projects.
One local developer commissioned nearly three dozen artists to cover Wynwood Walls, a free, outdoor complex showcasing the world's top street art.
Independent artists like Mast pay their way, haggle for a wall and barter for supplies. Some are lucky enough to be given free weatherproof spray paint cans by companies like Germany-based Montana, which sponsors artists around the world, though their murals may not last.
"Walls are getting done over, left and right, with total disregard," said David Anasagasti, a Miami-based street artist known as Ahol Sniffs Glue who complained Wynwood had become gentrified and over-saturated.
"It's getting kind of tacky," he said.
A handful of gallery owners have also begun shying away, citing rising rents, few art buyers and condominium development.
"It's not going to be Chelsea, it's not going to be SoHo," said Fredric Snitzer, who left the area three months ago. "It will be a nice enough neighborhood but it is not going to attract good quality galleries."
Still, the graffiti art is welcomed in a city trying to enhance its fun-in-the-sun image and become a more cultured metropolis.
"It's not the same Wild West it once was," Fairey said. "But I have always been a populist. I love the idea of democratizing art. Wynwood is a template, and there are lots more walls out there."
While Wynwood's street art-friendly attitude has made Miami a popular venue for graffiti artists, it can still be a risky business.
Activists held a vigil on Friday for Israel Hernandez-Llach, an 18-year-old graffiti artist who died after being subjected to a Taser by police who found him spray-painting an abandoned building on Miami Beach in 2013.
A Miami Beach bar's staff arrived on Tuesday to find that a "guerrilla" artist had hidden inside a bathroom overnight to emerge after closing and paint a pattern of black cryptic symbols on its walls.
"Art Basel brings out the crazies!!!" Purdy Lounge manager Aron Epstein wrote on Twitter. The work, believed to be by an artist called Zeem Rock, was so "cool" that Epstein said he was considering leaving it up.
"Well played sir, well played indeed," he added. (Additional reporting by David Adams; Editing by David Adams and Will Dunham)