I have a V4 a V4+ and a BIG Fogger and none of them have given me any trouble. No rust, no bad machined juice or air channels no stripped screws. I agree with TBEV only floods during fill which clears after a few drags and I use a syringe. No dry hits. I run 100% VG that I mix and flavor myself - using flavors from VapingZone - Tobacco, Dunhill, Klondike, Viginia Flu-Cured.
Sorry to see folks having these problems. Either poor quality control in manufacturing, variations from different manufacturers or knock offs.
Would still like to see spring loaded posts and top fill ports with thumbscrew or twist crown from Yiloong for a total tool-less RBA.