Actually, I tend to take the exact opposite tack.
I almost ALWAYS carry a mod with a tank, because people can't confuse it with an "analog" cig, and it makes for a better "ice breaker" to open up dialogs and "educational opportunities".
If someone is going to accuse me of "smoking", the last thing I want to do is be immediately on the defensive because I'm carrying a small, white 901 cig-a-like. If I'm vaping an eGo or a 18650 VV mod with a Vivi Nova, there is NO WAY anyone can say "I thought that was a cigarette". If someone is going to get all up in my grill about "smoking", they are immediately going to look unreasonable and foolish to bystanders, because I'm onbiously NOT "smoking" a cigarette. And when they give me that "deer in the headlights" look when I start to explain what a "personal vaporizer" is and how it works, they look (an hopefully feel) even more foolish and ignorant.
The key to dealing with unreasonable ANTZ is to craft the situation so that THEY look like the aggressor, the oppressor, and the inconsiderate, ignorant, rude person. That way I look like the "victim" to onlookers, and the entire public opinion dynamic is instantly shifted in my favor. THEY are coming into the situation on the defensive before they even know it, and all I have to do is be polite, speak in even, soft tones, and explain what I'm actually doing, and how it is 100% legal and not a threat to their health or the environment.
Successful activism is NOT about "facts" or "truth" or "statistics" or "winning the argument". It is ALL about PERCEPTION, and if you can put the other person in a situation where, to the public, THEY look like the aggressor, the rude one, the inconsiderate, ignorant neanderthal, then you've alreay won 99% of the battle. Answering them with calm, measured tones, peppered with some technical jargon to make them look even more ignorant, and then asking them if they are REALLY that offended by the aroma of coffee/caramel/watermelon or whatever you are vaping will just give them even more rope...
It's ALL about perception. Be mentally prepared. DO NOT respond to aggressive ANTZ with aggression or objections to their objections. Ask them questions--"Do you know about Personal Vaporizers and how they work?" "Did you know that PG is used in ALL medical products that are delivered in vapor form, like asthma inhalers and nebulizers?". Let THEM rant and rave. Let THEM make wild accusations and spew BS. Let THEM dig their own holes, and look like the unreasonable one.
It's ALL about perception. I can not stress that point too strongly. And when the Vape Community "gets" this one simple fact, and starts to implement it--IN PUBLIC--things will start to change and turn in our favor...