Well for me the shamrock shake was fine, I think it was the chocolate flavoring. Haven't really found one that truely hit for me. I also am using 6mg in my dripper, and I can drip 11 if I don't want to puff and drip a whole bunch.
I have never had a hard nic taste from KJ's juices. The best way to identify the nic is to vape unflavored base. IMO the nic is pretty darn tasteless as I have about 100 bottles and don't taste it, and never have. I know it is there as I get the "sweats" if I drip too much in a row. (12-6mg/mL) I have had some junk juice from the gas station or tobacco store where it is clearly present as a "peppery" taste just like that crappy tasting gum.
The mint overpowers the underlying shake flavor (to me atleast). I cut some Shamrock down by 40% by adding some VG and the mint is still clearly present. The chocolate is like eating a spoonful of hersheys. The peach is really fresh, but IMO the shake flavor is rather dominant. Same with the strawberry. I continued my shake testing with the Black Raspberry and again I thought holy geez what a nic taste, but though back to a few months ago about that same taste with the peach and strawberry and had a light bulb moment. It is not the nic, its the shakes themselves!
Now if you are having issues with chocolate that may be another issue altogether. I have found that KJ's chocolate flavored juices tend to funk coils really quickly and that may be a cause for an "off taste" that isn't related to the unfamiliarity to the characteristics of the shakes. I usually get about a tank and 1/2 before I need to dry burn the coil as it has crusted over a bit and tastes pretty foul. For me this is for ALL flavors with chocolate. I have tried numerous builds, coils, wicks, and etc. It is just the price of vaping a tasty chocolate juice IMO.
I don't know how else to describe the shake flavor other than a perceived nic overload, but indeed it is not the nic. Blue Moon also has a sliiiight hint of it, but nothing like the shakes.
This is just my observations as we all know taste is subjective not to mention all of the different devices that we use. I don't work for KJ and am by no means bashing the shakes as I like them all.