For years now I have been consciously limiting my enthusiasm when presenting things I've learned to others after being bitten by this problem. Some personal examples:<p>* linux - the freedom it gave me to build my own computing astounded me. I praised it in every direction only to find people that want all the benefits with no effort. I had to configure their systems to prove linux was any good. When I started telling them the benefits require personal tinkering I was attacked for "being an elitist" and linux was said to be actually full of things that don't work. Now I present it as a geek thing that is of no relevance to the general public.<p>* motorcycles - I now have the following presentation when people ask me about my experience riding: "It's not like on TV, when it's hot you sweat, when it's cold you freeze, when it rains you're wet and it's quite dangerous on top of it." That's after my enthusiasm convinced some people to buy motorcycles and crash because they didn't take riding seriously enough. They thought they where cool toys.