Also, many vendors these days will sell through Amazon.com. It's a lot safer purchasing through Amazon.com since they are very intolerant of bad merchants.

From the original NY Times article:

In other words, Mr. Borker is perfectly capable of minding his manners. And he does so, right now, with every order that comes through a store he runs through Amazon.com’s affiliate program. (He declines to provide that store’s name.) He handles those transactions like a Boy Scout because Amazon doesn’t mess around, he says — the company just kicks you off its site if you infuriate customers.

How does that work though? Doesn't this method just return negative results by definition? There are a lot of results confirming that "apple sucks" or "toyota sucks".

Genuinely interested, because the only reliable way I've found is to spend hours and hours reading through niche forums and reviews, and for every great product there are plenty of bad comments out there.

Of course it returns negative results. The key is not to take them blindly.

If they mention specific facts (extra bonus for verifiable ones), do not sound like ones written by poopheads or mass produced by competition, then it's a very strong red flag.

Things like unfavorable terms of service or checked-by-default, hard-to-notice checkboxes subscribing you to worthless additional services are easy to verify, even if you give zero trust to anonymous reviews.

You then have to read the review and see the content.

You contrast "one star, it doesn't this obscure thing it didn't to do but otherwise it's great" versus "one star, it fell apart in three days, seriously" and get the idea.

It's a constant battle, altogether.

Hopefully, the Internet will continue to be deeper than the scamsters' ability to game. And hopefully Google will keep helping in this regard.

And can it recognize a double negative, as in, "all of these Apple sucks sites suck"?

If you can do decent sentiment analysis though, you could lower the page rank granted by a link by sentiment of text in its proximity, while not lowering the rank of the page that contains the negative sentiment.

Me too. They should be able to distinguish between a negative review and the negatively-reviewed website it links to easily enough. Distinguishing the negatively-reviewed website from other links on the reviewing site could be a bit trickier.