This is one of those embarrassing niches that is full of desperate buyers.
If you visit the Google Keyword tool you'll see plenty of keywords, many of them long tail keywords which are easy to rank for.
Another name for excessive sweating is hyperhidrosis. Lots of keywords to target.
Now you can create an affiliate site if you want, OR you can create a quick 250+ word press release. OnlinePRNews.com is a good site as you can include a live URL in the contact area and direct visitors to click on your link.
Either write one yourself or get someone to write one for you on Fiverr.
Now start a campaign online, whether it's PPC, display ads, whatever....and use the press release as your landing page. Why?
Well press releases are trusted far more than a page on an unknown page (i.e your affiliate landing page). Your article is seen as being a news report rather than an affiliate review.
You'll find a few products on Clickbank in this niche.
Desperate buyers + press release = easy sales.