There is a huge variance in quality from every manufacturer out there.  I've got 2 510 attys my wife has used for over 4 months now that were "cheap knockoffs" and I paid $2 for them.  I'm staring at 4 blown up Joyes and 2 dead boges just from last week on an order I placed.  I have one cisco 306 I have been drowning for 3 months, and it still tastes fantastic, never cleaned it.  I have the 2nd cisco 306 from the exact same order that didn't last a week.  I have a few differe Ikenvapes that lasted a long time, next order I placed I had 2 that died in a day.
It's frustrating, and horribly random it seems. Cartomizers are a tad bit better in that they cost 1/5th as much as an atty, so those just hit the trashcan.  It is the same experience with those as the attys.  I 
vape 6ml a day though, and I tax the hell out of them.  My wife just vapes her little pink ego 2ml a day.  Maybe I could get hired to Stress Test these attys/cartos for everyone... or at least get a discount on my second order since I already did test pretty much everyone of them out there.
They are ALL made in china, you win some, you loose some.  Find a vendor that at least lets you mail the DOA ones back.