I lived there for 7 years and my wife is Thai.. Electronic Cigarettes are "illegal" in Thailand but "Unregulated" so basically your free to use them but they are not sold at 7-11 or anything because they said the Thailand tobacco Monopoly was going to loose money. So by saying that it keeps it from exploding.. I vape everywhere we go and used to smoke everywhere to (designated areas) .. Basically they care less if you vape or not but they do not want you to take away from the cig industry
My experience is the same. Thai people mind their own business and don't care about anything for the most part. Police are the same. If it is not part of "their job" they do not enforce any law. There is currently no agency with the power to enforce the ban so it is basically toothless with the exception of customs through the airport. If it comes by regular mail, the worst that ever happen to me is to pay customs fees of 30%. There are more Thai vendors then most people are aware of and I have compiled a few that I have dealt with and trust. There are no stores except for junk beginner e-cigs sold at electronics vendors. But you can get a good amount of products including the Siam Mods, Thai made and designed Map Tanks, Juices of various brands, cartomizers, clearomizers, AW batteries and other quality products.