I think that being ethical is important if you want to develop a reputation and not harm other people for your own benefit. For example, I believe heavily in ethical blogging and ethical business practices in general. But, I don't believe that making something like an acai berry site is necessarily unethical unless you misrepresent the product in a way that could be harmful to someone or employ deceptive tactics. Personally, I once posted on Yahoo! Answers quite a bit with a link to an acai berry site. It resulted in a handful of sales, but I didn't personally do anything unethical.
On the other hand, I made a natural male enhancement site a while back - I posted all factual information on the site and made it very useful to visitors and simply recommended exploring the option of male enhancement products, and then made a few 'recommendations'. xD