It depends on the quality of the charger. It's difficult to tell without checking it out with instruments. But if you can get your hands on a multimeter and measure its voltage it could give an indication. If it provides between 5V and 5.2V or so, and not something wildly different, then it may be OK. No guarantees though. Many China-made chargers are total rubbish, while others are completely fine. If it was provided as part of a kit with some decent, well-known product, then it's probably OK as well.