Not all USB chargers are the same

I always thought that, after all, a $2 Chinese USB  charger is almost the same of a $30 Apple USB charger.

Then, I read this article where various chargers are compared... and I was shocked to see the quality of the current given to my handset. 

That's why when I charge my BlackBerry Dev Alpha with a $2 Chinese USB charger the touchscreen goes nuts!
Since it's a prototype, it doesn't have CE or FCC certifications and it's not shielded by electromagnetic interferences, and the very bad quality of the charging input has a noise that makes impossible to use the capacitive touchscreen.