I, too, like to use dry humor, and I have tried it on the Internet, but I find that sometimes people don't get it. And I generally don't have that problem in real life. And I had even put a grinny face (

) after what I said on The Internet at one point. In cyperspace we can't see people's facial expressions and hear the tone of their voices. So, I think we need to be more careful when we are not in direct contact with people.
I don't like sarcasm, though, unless it is something between two people who know it's in fun. Often times, as was said, sarcasm is just mean and passive-aggressive. I have to say I do like shows with some sarcastic humor, though! ("The Big Bang Theory" comes to mind, as well as the late night talk show hosts.)
I am thinking that sarcasm is a type of dry humor, but the type that is more mean-spirited....
All right now, I don't want to see my last statement in quotes, followed by the words: "That is a really brilliant observation," unless you are actually confirming my astute cognitive skills!