From the Star Tribune February:
"TECH Only 12 iPod chargers left! After that you’ll have to look elsewhere for things that pop, sizzle, and burst into flames. A sample review:
This is a cheap imitation copy received just two days after the airing of a BBC documentary following trading standards where people's houses were nearly burned down by such items. This is not something that is a rip off and makes no effort to disguise the fact, this is a completely fake product with the exact same design and copied part numbers, CE logo etc from the genuine article."
There are numerous other reviews about cheap chargers for iPod, iPads and Laptops. And it isn't a generalisation to say "Third party chargers have a history of exploding." It is fact. Your chargers might not have exploded - yet. If you want to take the chance, that's up to you. But there's a reason electrical standards exist.