" You can use a trademark in a blog's name or in a blog title if it is relevant to the subject of your discussion and does not confuse people into thinking the trademark holder endorses your content.
Courts have found that non-misleading use of trademarks in URLs and domain names of critical websites is fair. (Bally Total Fitness Holding Corp. v. Faber, URL
http://www.compupix.com/ballysuck ; Bosley Medical Institute v. Kremer,
domain name Request Free Information about hair loss and hair restoration from Bosley). Companies can get particularly annoyed about these uses because they may make your post appear in search results relating to the company, but that doesn't give them a right to stop you.
Sometimes, you might
use a trademark without even knowing someone claims it as a trademark. That is permitted
as long as you're not making commercial use in the same category of goods or services for which the trademark applies. Anyone can sell diesel fuel even though one company has trademarked DIESEL for jeans. Only holders of "famous" trademarks, like CocaCola, can stop
use in all categories, but even they can't block non-commercial uses of their marks.
While trademark law prevents you from using someone else's trademark to sell your competing products (you can't make and sell your own "Rolex" watches or
name your blog "Newsweek"), it doesn't stop you from using the trademark to refer to the trademark owner or its products (offering repair services for Rolex watches or criticizing Newsweek's editorial decisions). That kind of
use, known as "nominative
fair use," is permitted if using the trademark is necessary to identify the products, services, or company you're talking about, and you don't
use the mark to suggest the company endorses you. In general, this means you can
use the company
name in your review so people know which company or product you're complaining about.
You can even use the trademark in a domain name (like walmartsucks.com), so long as it's clear that you're not claiming to be or speak for the company.
Since trademark law is designed to protect against consumer confusion, non-commercial uses are even more likely to be
fair. Be aware that advertising may give a "commercial" character to your site, and some courts have even gone so far as to say that links to commercial sites makes a site commercial.