|This page in a nutshell: It is OK to refer to trademarks, but trademark symbols should not be used.|
Trademark is a legal instrument that companies and individuals can use to preserve their own or their products' reputations. This guideline discusses the use of trademarks in Wikivoyage.
It's perfectly OK to use a trademark to refer to the object or company. That is, if you're talking about Disneyland, call it Disneyland.
Firms and individuals often use the ® (registered trademark) or ™ (trademark) or ℠ (service mark) symbols when referring to their own products, names, or services. This notifies the public that the word or image used is a trademark.
However, no one else is required to use the ™ or other symbols. Since typically only trademark owners use these symbols, they usually end up on promotional literature, ads, boxes, etc. Using these symbols on Wikivoyage makes it look like promotional literature, or that we're pandering to the trademark holders. They also clutter up our guides with extra "noise" characters that don't serve any purpose. For these reasons, avoid using the ™, ®, or ℠ symbols.
Promotional literature also often has trademark notices at the end: Foo and the Foo logo are trademarks of The Foo Company. Again, we are under no obligation to make these statements, so we can safely avoid trademark disclaimers.
Trademarks used as generic nouns
Some trademarks (Jacuzzi, Jeep, Kleenex etc) are used as generic nouns in daily speech. When describing a generic product, a non-proprietary noun (hot tub, terrain vehicle, facial tissue) should be preferred.