[help with my vamo v5]

Okay, I'm curious. I have a Vamo V3 and have pretty much exclusively used stacked 18350's (button top, 700mAh) with no problems. I have never put foil between them, the thought never crossed my mind,

Why is stacking bad, exactly?

[Worst tanks and why?]

I have owned several tanks:

Vision Vivi Nova: hated it. Dry hits, super leaky. Bad taste (but that may have been the juice I was using at the time)

BCC Mega: One of the first bottom dual coil tanks, I believe. Coils are similar to EVOD/Protank, but instead of threading, they push in. Leaks like a sieve.

KPT2: I used this one for a long time, but leaky and gurgly and dry hits. Inconsistent coils. Building my own helped with dry hits and coil life but not leaks.

KPT3: Still leaky but not as bad as KPT2. Had to turn my wattage up to 12 (on 2 ohm coils) just to get any flavor, at the expense of dry hits.

Anyvape Davide with Aspire BDC adapter and coils: best so far. Rarely leaks, when it does it's operator error. Flavor is muted however. Tight draw, which I like. Difficult (but not impossible) to rebuild coils.

I have a Kayfun clone coming, should be here any day now...