ok juice is super easy to make. if everyone knew how easy it was, more people would do it. then most brick and mortars wold be out of business.
Juice is what pa s the bills. Mods and tanks do not make much profit.
it costs a store about $3 to make a 30ml bottle of juice and most sell it for 10-20
where a piece of equipment they sell for $20 costs them usually 10-15
Vapors spend alot more on juice then equipment
therefor for brick and mortar stores, its all about the juice
So mixing behind a curtain or a back room out of sight makes sense to me.
this does not mean something fishy is going on.
Its just they dont want you to know how easy it is
Also doing everything in view of the customer gives away the recipe, the brands of flavorings, approximate amounts etc
IMO if someone has gone through the trouble of setting up a brick and mortar, they are probably going to be trying to have a fairly clean environment to mix juice in. B&Ms are expensive to keep open, so they have to worry alot more then someone with just a website.
To me the whole hiding behind a curtain is more to protect their investment in a business, then it is to hide something fishy
What would concern me is 15 minutes to make one bottle of juice, unless that was just for the purpose of making it seem harder then it is.
If your concerned ask to see the mixing room, tell then you are concerned . try to be nice, because you could easily come off as accusatory. Say you want to see where the juice you be buying all the time is mixed, so when people say things like, "you dont know what's in it" you can reply "yes i can I have seen where it is made, I know the person who makes it. Have you seen where the sausage patty on your egg mcmuffin is made and who makes it?
With a line like that you may even get a demonstration.