I'm constantly amazed how many people doubt that tobacco taxes and soda taxes work, even people who are educated and listen to empirical research in other parts of their lives. The reasoning seems to be that because they don't feel particularly price sensitive --- making purchase/quantity decisions based on goods' prices --- they aren't price sensitive. Likewise, because they have seen people continue to smoke and buy cigarettes at high prices, they believe few people are smoking less or quitting smoking due to tobacco taxes.
Campaign for Tobacco Free Kids put out a new report on this subject, documenting simultaneous decrease in smoking and increase in revenues from tobacco taxes. The economic research on the subject indicates that soda taxes could be similarly effective.
Going the other way, many people don't perceive expensive produce as a barrier to produce consumption. If they choose to buy more expensive produce (e.g., shopping at a more expensive store, only organic/local), they don't see that their decision to buy more expensive produce could decrease their fruit and vegetable consumption. At most levels of income, probably they will buy less if the produce costs more. Certainly they would buy more if it were cheaper: I've noticed that yelp reviews of lower cost produce shops and supermarkets commonly remark that they can get several huge bags of produce for the cost of one bag of produce at their regular store, and that they do get more when they shop at these stores (e.g., this one in Chicago).
People who otherwise listen to economic research and use it to guide decisions and opinions in the rest of their lives, and who believe in things that they can't see like germs, atoms, and molecules, somehow don't believe in price elasticity because they can't see it. I wonder if anyone's researched the impact of belief in price elasticity on economic behavior.