Great thread to start Astro, all this while i had the same question in my mind too. I am a total noob with matters related to websites and online businesses. Your list of really dumb questions here opened new arenas of knowledge gaining to me. :-D
And, oh yes, the crash course here is great! I...
As seoways pointed out, its legal as long as people find your way of approach unethical.. Point to consider is, you need to ensure the product you intend to sell satisfies the end viewer's requirement and he doesn't get compelled to report/complain about them.