Do the math and you'll see. Let me explain. Around 18-24 months ago, I remember seeing a post by Jeremy Kelsall saying that he was killing it in a specific hot niche with a ClickBank product. I remember how impressed I was because he had over $1K in sales in a single month if I remember correctly. Now I sent him a PM and told him that I actually was in the same niche and I didn't make a dime so I thought it was a bad niche for me and I dropped it. I thought I was bada$$ because I had written 20 high quality articles and distributed it to the top 20-30 article directories. I was going to make BANK, I thought Anyway, after that dismal failure, I asked Jeremy about it and I asked him about his articles. Turns out he wrote over 1,000! HAAAA! I wrote 20! OK, well, I failed because I didn't do the math!
So, before you go on thinking that you've failed, just remember, DO THE MATH! Sometimes it takes a few thousand visits to get a sale. Figure out how many articles you need to make that happen. I say articles because if you don't use a free promotional method, you can lose your shirt with PPC.
Now, go out there, make some money!