Michael,

Thanks for ASKing.

As I mentioned already, but consider it better placed in this thread, one method is for finding a product which sells (it might not be top selling, but does sell) is ...

1: Do a Google Search for something. For example, "How to repair rust".

2: Save a copy of the Google Ads in a Text File. In this case there is Only 1 ad which reads...

Repair & Prevent Rust Now
Stop Rust For 10 Years, Guaranteed.
No Prep, Easy To Apply & Maintain!
www.RustBullet.com

Note: A Search for Rust Repair got three ads on the side...

eBay Rust Repair
Make money, sell your Rust Repair
Compare Offers, Get Our Best Deal
www.eBay.com.au

Zero Rust for rust repair
Corrosion Coating, rust protection
barrier at the steel surface level.
www.zero-rust.com

Easy Quick & Inexpensive
Treat-Stop-Prevent Rust & Corrosion
for tough safe & lasting protection
www.floodaustralia.net

3. In two month's time do the same search. In fact, it's wise to save the Search itself - copy the location bar - and then paste that back-in two months down the track. If you see the same ads from the same company you Know they are either Making Money (people are buying their stuff) - or - they are insane and are spending money to get Brand Awareness without the matching sales (something the Big Boys do but the small guy generally will not do).

If you assume they are making money you have identified a Viable Market. A Market and often a Product people are buying.

4: Check out their website for Finer Details - how they market it on the web, do they do email as well, bonus items, etc. Even BUY their product as Additional Competitive Research.

This should not only find you a Viable Product but also show you Part of How it is marketed. And I say Part because you will only be aware of the small marketing methods you have seen. They may also use Offline methods you aren't aware of.

There are Other Methods, but let's see what others share to see if those other methods are revealed.

Michael Ross