Of course, Kuala Lumpur is very big, and not every place is unsafe. Porcelain Factory Street, a place with many China people, foreign workers and tourists, is also a tourist attraction, which can be called a mixture of people and snakes.
There are many delicious foods and many fakes. Foreign workers here will not cause trouble to tourists (mostly from Bangladesh and Nepal), but just work here. There are many pickpockets (most of them are addicts), so you should put away your wallet when you pay for something.
But don't be too scared. After all, you are not afraid of thieves if you take care of your things. Besides, there are many fakes, so we don't want to buy anything here except food.