yeah, I've heard that. I've also had a penny set off the metal detector. I wouldn't risk it.
I had to show security my K100, because it's an odd shape (
http://www.p-vaper.co.uk/WebRoot/St.../181B/08BA/9098/0A0F/1119/89C0/Black_K100.jpg) But only once. Everything else went through without a problem.
There are two hard and fast rules you need to pay attention to.
1. Eliquids in carry-on luggage follow the rules for all liquids. Put juice bottles and filled tanks in your little plastic bag along with your toiletries and medicines. This only applies if you want to have the eliquid in carry-on; there is no problem having as much as you want in your checked bags, in tanks or bottles or whatever.
As has been said, tanks will probably leak so double bag them.
2. Batteries (eg 18650s, not EGOs) that are not in devices, MUST be in carry-on luggage, and they MUST be appropriately packed. This is an international regulation. Appropriate packaging means a purpose-made battery case or retail packaging by preference, although taping the ends and putting them in individual plastic bags is acceptable.
I've had security ignore any number of minor infractions -- tanks not in the bag etc. -- but that's human nature and discretion, not something to depend on.