There is certainly no shortage of accessory options for your devices. You can get wall chargers, car chargers, and cables for dirt cheap; how can you resist saving a lot compared to the same accessories sold by the device manufacturer. This desire to save could bring on costly risks though. Costs like having to completely replace your device, or other belongings.
So what chargers are bad?
In my opinion, you should avoid the cheap chargers or cords manufactured by brands you’ve never heard of. This consists mostly of products on amazon, in drug stores, gas stations, etc. Anywhere that tech accessories are displayed for the purpose of impulse purchases. There is no brand trust with those products, just a low purchase price. Belkin, Apple, etc have a lot more riding on their reputation for reliable device accessories than some random company from China.
So what exactly can happen if I use a cheapo charger from Walgreens?
First and for-most, you could damage your device. I've seen this happen to my step father who used a cheap gas station car charger and fried his iPhone, and had to by a whole new phone. These cheap charger and cable manufactures use cheap materials and leave out technology which helps provide a steady stream of power to your device.
Secondly, you could be injured by these products. There are plenty of cases involving people using cheap accessories that have been electrocuted…to death. Some had the headphones melt into their ears. This article from Vice is a good example.
Third, but equally as bad as the previous two is the possibility of damage to your home. A wall charger that experiences a spike in electricity could melt or catch fire.
Just because I use a reputable brand doesn't mean I'm 100% safe…
This is true. You aren't 100% safe using any charger. There have been cases where Apple's own wall chargers have short circuited and caught fire. The biggest difference though is because Apple has a reputation to protect, they will likely cover damages and/or replace the malfunctioning product. The little no name company from china will definitely not do that. All they would have to do is retire their current name and re-open as a new company and continue their sales.
Not all charging devices are created equal. Though the price may not be as desirable, buying charging accessories direct from the device manufacturer or a long time 3rd party company is a better choice. Should something malfunction, they will be more likely to make things right.