For the same reason PayPalSucks.com has been online for 15 years without being sued: it's not trademark infringement. Nominative use (using a mark to refer to that product) and fair use (criticism and commentary, protected by the first amendment) are affirmative defenses to trademark infringement. Registering a trademark doesn't prevent other people from using that word, only from using it in ways that are likely to cause consumer confusion as to the source of some goods or services.
This isn't using a single mark to refer to a product for criticism and commentary; this is using an unlimited number of marks for promotion of the registrar's sites. (In addition to using the mark in the ways you mentioned.)
That is, the registrar's goal isn't to refer to PayPal, but to use the domain PayPal.sucks (and potentially every protected mark plus ".sucks") to draw traffic.
I guess the legality of this use will need to be decided by the courts.
You're allowed to criticize any company you like (as long as you don't lie), and you can even profit by doing so. For example, media companies can sell newspapers containing negative reviews of trademarked companies, and make money from it.
For trademark infringement, there has to be "likelihood of confusion", i.e. your use of their trademark could lead to people thinking that your goods/services originated from the trademark owner. In the case of someone explicitly critisizing a company, this could never be argued.
Have the courts ever ruled that you can market a series of magazines/etc called "_____ sucks"?
It's an interesting legal question, essentially arguing that adding the magic word "sucks" allows using trademarks to promote their site (perhaps even to advertise competing products).
The law is fluid, and nominative use is a fairly new legal idea. We're not going to settle the question here, but it will be interesting to see what the courts decide.
You don't need a court ruling to allow you to do something. It's the other way round.
Of course it's fine to market a series of magazines called "_____ sucks". It's just expressing an opinion. Trademark law doesn't come into it, unless the trademark owner can prove that consumers might reasonably think your use of their trademark is somehow authorised or affiliated with them. In the case of "____ sucks", that would be self-evidently not the case.
I didn't say it was a free pass to do anything. You can't lie about the company, for example. But that would be libel, not trademark infringement. As long as it's obvious to consumers that your use of the trademark is not on behalf of or authorised by the company, then it's not trademark infringement.
And yes, simply adding "sucks" would pretty much always be a free pass against trademark infringement , except in really contrived scenarios, like if the trademark was a brand of vacuum cleaners :)
That said, the Dumb Starbucks example is interesting, I think that's in a grey area, the kind of edge case you're talking about. Starbucks might well be able to demonstrate that some customers thought it was official (albeit obscure) marketing effort by them, especially because it's a coffee shop.
The show "nathan for you" made a parody starbucks called "dumb starbucks" that mimicked starbucks exactly but put dumb in front of everything. starbucks didnt sue them so no rulings came out of it, but it is exactly what youre discussing. https://en.wikipedia.org/wiki/Dumb_Starbucks
"Lawyers who specialize in trademark and copyright law say not so fast. While parody is generally a protected form of speech, there is no clear-cut legal definition of what separates legitimate parody from trademark infringement. The reality is, any infringement case that makes its way into a courtroom will be evaluated on its own merits, with judges weighing various factors against a body of existing legal precedents. Historically, cases could go either way."
