Sand in Water

New York City has many visitors. It is an important part of our economy. And generally speaking we embrace all - outsiders, outcasts, iconoclasts. The melange of characters and people already here dilute things that it is difficult for one person or group to really ruffle any feathers. 
But there are abrasives that even in New York City can rub one the wrong way. And one of those things are motorcycle gangs. They seem curiously out of place here but for the most part are tolerated. Dilution in the world of New York generally makes them a fleeting image. They frequently congregate in various locations such as near Gray's Papaya in the Village. Time is spent eating, cavorting and sporting their hardware. And off they go in a roar.
However, the roar of a pack of bikers is one thing but when some use straight pipes (no mufflers), the sound can be deafening. It is illegal, but prosecution is difficult. I have witnessed sounds that are literally like explosions. I am sure most bikers are law biding, but the few bad apples really spoil the barrel and the outlaw image is strengthened.
There are things that can not be diluted. Like sand in water ...