Good question. I mean that you can easily find low-competition keywords that are easy to rank for on Google (on the first page), you get 500-1000 pageviews per article (on average), and make a few hundred to a few thousand dollars per month from affiliate commissions.

Essentially, it is seeing the signs of success early on your blog.

If you start to rank and get thousands of pageviews with a few months, that's a great sign. You can still make good money if your site takes longer to rank, but I'm just talking about finding a rare very profitable site in this article.

I hope this makes sense! :)