Is Affiliate Program outside network trustworthy ?

I am promoting some physical products. I have tried to search a lot but it seems like those products are not advertised on any Affiliate Network like CJ, Rakuten, ShareASale...

So, I tried to search on Google "product + affiliate program". There were a lot, however those affiliate programs are self-hosted by the merchants. It took me like 2 minutes to register then they accepted my application automatically, without sending any confirmation email !

My concern is, is there any chance that they scam me some dollars (like, I refer 10 sales but they count as 5 only), or worse, they don't pay me ?

Have you joined any program that is outside the network ? What is your experience ?

P/s: those merchants are very large, they have big stores located on USA, with detailed address displayed on Contact Us page. They received a lot of positive reviews from the customers. However, how they treat their affiliates is another story.

Anything you do using any companies affiliate scheme you have to trust them to be honest ( same as they trust you not to try game them ).

At the end of the day, you'll need to bite the bullet and take that leap of faith.