I've observed similar products myself, often ones that are more successful versions of my own creations. I've seen stuff built with spaghetti PHP code, yet it was marketed well and more people were paying money to use it than my own. Yet when I looked at it, the first thing I saw was an SQL injection vulnerability that would allow me to drop the entire database.
It makes me wonder though, if instead of looking at entrepreneurship from the software development side of things, maybe instead I should be trying to build a marketing and advertising agency that builds software. These types of companies seem to make more money than I do.
Yet at the same time, in the marketing companies that come to my mind, the weaknesses in their products tend to be sustainability. I think overtime customers are going to become frustrated with their lack of good support and ability to maintain code and add new features.
Just my thoughts when reflecting on all of this. :)