The Nature of Ideas

I've been thinking about ideas a lot. Just what makes them good or bad, or more specifically, what makes them successful or unsuccessful. I've been able to make money with my ideas by selling slogans to t-shirt companies, but I don't know how I got so lucky to do that, and why that appears to be a special talent.

On the main site I use to create slogans (Threadless, under Interesting Places) there is a large gap between those who are successful with slogans and those who aren't, or those who 'get it' and those who can't. Part of this is due to the amount of exposure you get within the site, but a lot of it is from apparently just not getting what a funny idea is made out of. I'm not really sure of what works myself, I still have failures, but do better on average than most. Maybe this is just having a sense of irony, but if that were true, I'd think more people would achieve success the way I have. So it must be deeper.
Why is my brain (and some brains in general) hardwired to understand funny? More interesting, perhaps, is that I'm not really sure why I can be funny. It just flows out in my reactions (how is there a divide between situational comedy and written comedy, a topic for another time), rarely am I funny consciously. I'm terrible with telling jokes, and I don't really spend time thinking about a slogan, I'm either inspired in pieces and fill in the rest, or the whole phrase comes to me. How can I be successful and have almost no insight into how I got there? It's a near out of body question, one I'm obviously not prepared to answer.
I posed this question to my dad the other day, "Do you think I'll be able to live off my ideas?" It's the question that's gotten me to thinking about ideas in general, and just what they are and the power they hold. How can an idea I have be any more powerful than someone else's? Or why can mine hold more substance, and most importantly, how can I tap into that?
I want to make a difference with my ideas. I don't want to change the world, necessary, but I want to think about the world and get paid for it, while making others think about the world and ideas. That is the goal, but how do you reach it? Can you wait for inspiration or is it possible to dig into your own brain and pull out an idea, and create a function and system to put it into motion...That is what I want to know: How far can you go with the idea of ideas, just how much of an idea tangible and how much you need to build around it. How far down does the rabbit hole go...